Whom does YHVH address when he says ""See, the man has become like one of us, knowing good and evil"?
I know the Christian rationalization that would see this as suggestive of the Trinity, but remember the historical context: we're talking about people who were utterly unfamiliar with that particular Christian concept.
"Us" is indicating the Trinity not other Gods, in fact that verse and a few others in the first chapters of Genesis are used to support Trinitarian doctrine of them, Genesis 1:26 is the most supportive.
The wording of the first commandment is also quite telling: "you shall have no other gods before me."
NOT "you shall have no other gods instead of me".
NOT "you shall have no other gods."
NOT "there are no other gods".
You don't get what the point of the first commandment was do you? It was not to state that there were no other gods, that was already well established among the Israelites when Moses penned the first commandment. The point of it was to tell us that we will not put anything above (or before) God in importance. For example if i put myself before god does not my ego become my god? You are once again taking the verse out of it's historical context and reading into it what you want to be there.
Exodus 12:12.
On that same night I will pass through Egypt and strike down every firstborn—both men and animals—and I will bring judgment on all the gods of Egypt. I am the LORD.
The Lord showed he was more powerful than the false gods of Egypt. I don't see the contradiction here, and i doubt most scholars would either.
Deuteronomy 6:14-15.
Do not follow other gods, any of the gods of the peoples who are all around you, because the LORD your God, who is present with you, is a jealous God.
John Calvin explains this verse well in his commentary:
14. Ye shall not go after. In this passage Moses commands the people not to turn away from the simple service of God, although examples of superstition may present themselves to their sight on every side. For this was a very destructive temptation, that none could be anywhere found who subscribed to the doctrine of the Law, although the respective nations had some religion, or at any rate the name of it existing among them. Since, therefore, these various forms of worship were so many temptations to forsake the right way, it was needful to provide against the danger betimes, and so to establish the authority of the One God, that the Jews might have courage to despise the common belief of all the Gentiles. A threat is added, that vengeance would not be far off if they should fall away into these superstitions, since God is a jealous God, and dwelling among them. As to the former epithet, I am about to say more under the Second Commandment. Meanwhile, let my readers observe that God is called jealous, because He permits no rivalry which may detract from His glory, nor does He suffer the service which is due to Him alone to be transferred elsewhere. When He reminds the people that he dwells among them, it is partly to inspire terror by reason of His presence, and partly to reprove indirectly their ingratitude, if they should forsake Him, and seek for themselves gods who are afar of.
Joshua 24:2, 14-15.
Long ago your ancestors -- Terah and his sons Abraham and Nahor -- lived beyond the Euphrates and served other gods. [...] Now therefore revere the LORD, and serve him in sincerity and in faithfulness; put away the gods that your ancestors served beyond the River and in Egypt, and serve the LORD. Now if you are unwilling to serve the LORD, choose this day whom you will serve, whether the gods your ancestors served in the region beyond the River or the gods of the Amorites in whose land you are living; but as for me and my household, we will serve the LORD.
Just because it says "gods of the Amorites" does not mean it recognizes them as true. In fact the audience the book was meant for would have obviously know that the "gods of Amorites" were false.
Judges 9:9.
The olive tree answered them, "Shall I stop producing my rich oil by which both gods and mortals are honored?"
First off i would like to point out that the paragraph this verse is in is a parable and everything can not be taken literally, and you would really have to go out and misinterpret this for it to confirm the meaning of other gods. Regardless, Pagan peoples thought that offering oil to gods would honor them and the author stated this no more and no less. He obviously did not confirm their existence
2 Samuel 7:23.
And who is like your people Israel—the one nation on earth that God went out to redeem as a people for himself, and to make a name for himself, and to perform great and awesome wonders by driving out nations and
their gods from before your people, whom you redeemed from Egypt?
Once again just because it uses the word "gods" does not somehow magically mean it confirms their existence.
2 Chronicles 2:5.
The temple I am going to build will be great, because our God is greater than all other gods.
Like before you are reading too much into the usage of the word "gods". Any Jew that read this would automatically tell you that by saying "our God is greater than all other gods." they are saying that the Lord is greater than the other false gods that people have created.
Psalm 86:8
There is none like you among the gods, O Lord, nor are there any works like yours.
Read farther in this Psalm and you will see:
8 There is none like thee among the gods, O Lord, nor are there any works like thine.
9 All the nations thou hast made shall come and bow down before thee, O Lord, and shall glorify thy name.
10 For thou art great and doest wondrous things,
thou alone art God.
David pretty explicitly indicates here that there is no God other than God. the word "gods" in the Bible does not usually carry the meaning of literal "gods". This is especially the case in the Psalms since they are poetry.
Psalm 138:1
I give you thanks, O Lord, with my whole heart; before the gods I sing your praise.
Like i said earlier the word "gods" almost never means literal "gods", especially in the Psalms. The word used in Hebrew that is translated "gods" can also mean "rulers". So the Psalm could very well read.
I give you thanks, O Lord, with my whole heart; before the kings I sing your praise.
Micah 4:5
All the nations may walk in the name of their gods; we will walk in the name of the LORD our God for ever and ever.
Once again you are reading too much into these verses the writers of the OT were fond of poetic effect. I will say it again just because it uses the word "gods" does not automatically mean that the Israelites believed other gods existed
Read all of these verses in context (especially the Psalms since they are poetry) and the meaning becomes clear, and that meaning is not henotheism.
Additionally i would like to point these passages:
10 "You are my witnesses," says the LORD, "and my servant whom I have chosen, that you may know and believe me and understand that I am He.
Before me no god was formed, nor shall there be any after me. 11 I, I am the LORD, and besides me there is no savior. 12 I declared and saved and proclaimed, when there was no strange god among you; and you are my witnesses," says the LORD. 13 "I am God, and also henceforth I am He; there is none who can deliver from my hand; I work and who can hinder it?" Isaiah 43:10-13
We see here that before the Lord no God was formed we also see that no God was formed after him, therefore there is only one God.
Also see these verses in Isaiah:
Thus saith the LORD the King of Israel, and His redeemer the LORD of hosts;
"I am the first, and I am the last; and beside Me there is no God."-Isaiah 44:6
"Fear ye not, neither be afraid: have not I told thee from that time, and have declared it? ye are even My witnesses.
Is there a God beside Me? yea, there is no God; I know not any."-Isaiah 44:8
However, one of the most telling verses is this one

salm 82:1
God has taken his place in the divine council; in the midst of the gods he holds judgment.
If you read farther you will see this
1 <A Psalm of Asaph.> God has taken his place in the divine council; in the midst of the gods he holds judgment:
2 "How long will you judge unjustly and show partiality to the wicked? Selah
3 Give justice to the weak and the fatherless; maintain the right of the afflicted and the destitute.
4 Rescue the weak and the needy; deliver them from the hand of the wicked."
5 They have neither knowledge nor understanding, they walk about in darkness; all the foundations of the earth are shaken.
6 I say,
"You are gods, sons of the Most High, all of you;
7 nevertheless, you shall die like men, and fall like any prince."
8 Arise, O God, judge the earth; for to thee belong all the nations!
In the context of this Psalm "gods" is used as a synonym for "sons of the Most High" which in turn means righteous men. So the line can read like this if it's meaning is interpreted. Furthermore the divine council is the council of Angels that surrounds God
God has taken his place in the divine council; in the midst of the righteous he holds judgment.
Before I stop further derailing the thread, I'll kindly point to the documentary hypothesis and its "heirs". That one, of course, is just talking about the Torah, not the whole of the Tanakh - but I guess you get the drift.
I read through it and it does not appear very convincing, It even says most modern scholars have abandoned it as a explanation. The fact that it is still a hypothesis after all this time makes it even more unconvincing to me, because if there is enough proof to make it a theory surely it would have been found by now. After all a hypothesis is a proposed explanation for an observable phenomenon.
I would like to ask this though. If the Lord was but one of many gods, why did the other gods not stop the Lord when he took over their lands? Why did they not ally themselves against the Lord and stop him when he began to spread across Europe? Surely a whole host of gods and goddesses could have stopped the Lord when he had but one lowly people to serve him. The gods of Egypt were much more numerous than the Lord and they had many more worshipers, but they still could not stop the Lord when he visited the plagues upon Egypt, why? Why i ask you, why could these other gods not stop the Lord?