The reason I don't downsize Rev 19 from "all people" to "some people", and downsize the "rest were killed" into "the rest of some of the people were killed" or "the rest of the army that is not -- all people" is because there is "no human" only ruined cities on earth after that event Jer 4:23-26
The reason you claim what you do is you won't deal with the context in either case.
Rev 19
"the rest" includes all that is left over - in Rev 19 -- so also "the flesh of all people, both free and slaves, and small and great.”
17 Then I saw an angel standing in the sun, and he cried out with a loud voice, saying to all the birds that fly in midheaven, “Come, assemble for the great feast of God, 18 so that you may eat the flesh of kings and the flesh of commanders, the flesh of mighty men, the flesh of horses and of those who sit on them, and the flesh of all people, both free and slaves, and small and great.”
19 And I saw the beast and the kings of the earth and their armies, assembled to make war against Him who sat on the horse, and against His army.
20 And the beast was seized, and with him the false prophet who performed the signs in his presence, by which he deceived those who had received the mark of the beast and those who worshiped his image; these two were thrown alive into the lake of fire, which burns with brimstone. 21 And the rest were killed with the sword which came from the mouth of Him who sat on the horse, and all the birds were filled with their flesh.
The angel calls with a loud voice and tells the birds to gather...why gather? Because the armies are gathering to one spot.
Rev 19:17 Then I saw an angel standing in the sun, and with a loud voice he called to all the birds that fly directly overhead, “Come, gather for the great supper of God
The birds are gathering to eat specific types of flesh, including that of horses. Why horses? Because they are part of the armies of the kings of the earth.
Rev 19:18 to eat the flesh of kings, the flesh of captains, the flesh of mighty men, the flesh of horses and their riders, and the flesh of all, both free and slave, both small and great.”
He announces this call to the birds, and then we see what they are going to eat:
Rev 19:19 And I saw the beast and the kings of the earth with their armies gathered to make war against him who was sitting on the horse and against his army.
The birds are gathered to this place because the armies are gathered to this place.
Rev 19:20 And the beast was captured, and with it the false prophet who in its presence had done the signs by which he deceived those who had received the mark of the beast and those who worshiped its image. These two were thrown alive into the lake of fire that burns with sulfur.
Two of the figures in these armies are placed in the lake of fire.
Then the "rest" are slain. The rest of what? The rest of the army just described, gathered together, with the birds gathered also to eat their bodies.
Rev 19:21 And the rest were slain by the sword that came from the mouth of him who was sitting on the horse, and all the birds were gorged with their flesh.
Jeremiah 4 "I looked and behold there was no human" only destroyed cities
23 I looked at the earth, and behold, it was a formless and desolate emptiness;
And to the heavens, and they had no light.
24 I looked on the mountains, and behold, they were quaking,
And all the hills jolted back and forth.
25 I looked, and behold, there was no human,
And all the birds of the sky had fled.
26 I looked, and behold, the fruitful land was a wilderness,
And all its cities were pulled down
Before the Lord, before His fierce anger.
You have divorced this passage from its context, and inserted it into Rev. 19-20, even though Rev. 19-20 do not quote or reference this at all.
The context makes clear it is speaking of earlier events, where the Lord brings judgment from the north against Judah:
Jer 4:5 Declare in Judah, and proclaim in Jerusalem, and say, “Blow the trumpet through the land; cry aloud and say, ‘Assemble, and let us go into the fortified cities!’
Jer 4:6 Raise a standard toward Zion, flee for safety, stay not, for I bring disaster from the north, and great destruction.
This is continuing the theme that started even in chapter 1:
Jer 1:13 The word of the LORD came to me a second time, saying, “What do you see?” And I said, “I see a boiling pot, facing away from the north.”
Jer 1:14 Then the LORD said to me, “Out of the north disaster shall be let loose upon all the inhabitants of the land.
Jer 1:15 For behold, I am calling all the tribes of the kingdoms of the north, declares the LORD, and they shall come, and every one shall set his throne at the entrance of the gates of Jerusalem, against all its walls all around and against all the cities of Judah.
Jer 1:16 And I will declare my judgments against them, for all their evil in forsaking me. They have made offerings to other gods and worshiped the works of their own hands.
This power from the North is going to lay waste to the cities:
Jer 4:7 A lion has gone up from his thicket, a destroyer of nations has set out; he has gone out from his place to make your land a waste; your cities will be ruins without inhabitant.
Jer 4:8 For this put on sackcloth, lament and wail, for the fierce anger of the LORD has not turned back from us.”
The cities in Judah will be laid waste because of the anger of the Lord, who brings armies from the north.
This is referring to the soon coming judgment brought against Judah by Babylon.
Jer 4:9 “In that day, declares the LORD, courage shall fail both king and officials. The priests shall be appalled and the prophets astounded.”
Jer 4:10 Then I said, “Ah, Lord GOD, surely you have utterly deceived this people and Jerusalem, saying, ‘It shall be well with you,’ whereas the sword has reached their very life.”
Jer 4:11 At that time it will be said to this people and to Jerusalem, “A hot wind from the bare heights in the desert toward the daughter of my people, not to winnow or cleanse,
Jer 4:12 a wind too full for this comes for me. Now it is I who speak in judgment upon them.”
Jer 4:13 Behold, he comes up like clouds; his chariots like the whirlwind; his horses are swifter than eagles— woe to us, for we are ruined!
Jer 4:14 O Jerusalem, wash your heart from evil, that you may be saved. How long shall your wicked thoughts lodge within you?
Jer 4:15 For a voice declares from Dan and proclaims trouble from Mount Ephraim.
Jer 4:16 Warn the nations that he is coming; announce to Jerusalem, “Besiegers come from a distant land; they shout against the cities of Judah.
A power that besieges, again a reference to Babylon. It does not describe the judgment in Rev. 19. There is no siege there.
Jer 4:17 Like keepers of a field are they against her all around, because she has rebelled against me, declares the LORD.
Jer 4:18 Your ways and your deeds have brought this upon you. This is your doom, and it is bitter; it has reached your very heart.”
They will be surrounded. This is happening because of their deeds.
Jer 4:19 My anguish, my anguish! I writhe in pain! Oh the walls of my heart! My heart is beating wildly; I cannot keep silent, for I hear the sound of the trumpet, the alarm of war.
Jer 4:20 Crash follows hard on crash; the whole land is laid waste. Suddenly my tents are laid waste, my curtains in a moment.
Jer 4:21 How long must I see the standard and hear the sound of the trumpet?
Jer 4:22 “For my people are foolish; they know me not; they are stupid children; they have no understanding. They are ‘wise’—in doing evil! But how to do good they know not.”
Crash upon crash, the whole land laid waste, describing the conquest of the cities.
Now you claim the following verses are a contextual island and speak of the 1k years. But that doesn't follow at all.
Jer 4:23 I looked on the earth, and behold, it was without form and void; and to the heavens, and they had no light.
Jer 4:24 I looked on the mountains, and behold, they were quaking, and all the hills moved to and fro.
Jer 4:25 I looked, and behold, there was no man, and all the birds of the air had fled.
Jer 4:26 I looked, and behold, the fruitful land was a desert, and all its cities were laid in ruins before the LORD, before his fierce anger.
He uses language of the pre-creation earth to emphasize the extent of the devastation. The cities are destroyed, as foretold at the beginning of the chapter. It is showing the aftermath of the sieging of the cities.
Jer 4:27 For thus says the LORD, “The whole land shall be a desolation; yet I will not make a full end.
Jer 4:28 “For this the earth shall mourn, and the heavens above be dark; for I have spoken; I have purposed; I have not relented, nor will I turn back.”
The heavens and earth are said to mourn because of the judgment poured out. But He will not make a full end.
Jer 4:29 At the noise of horseman and archer every city takes to flight; they enter thickets; they climb among rocks; all the cities are forsaken, and no man dwells in them.
The cities are abandoned as it is seen the forces are overwhelming.
Jer 4:30 And you, O desolate one, what do you mean that you dress in scarlet, that you adorn yourself with ornaments of gold, that you enlarge your eyes with paint? In vain you beautify yourself. Your lovers despise you; they seek your life.
Jer 4:31 For I heard a cry as of a woman in labor, anguish as of one giving birth to her first child, the cry of the daughter of Zion gasping for breath, stretching out her hands, “Woe is me! I am fainting before murderers.”
This theme has been stated before by the prophets. God's idolatrous people who turned to the gods of the nations are now being destroyed by the adulterous lovers they turned to instead of the Lord.