God chose the Hebrew people due to one man's obedience. Abraham left false gods to follow the Lord's voice. It says in scriptures that God knew Abraham would teach his household to follow as well.
Why didn't God talk to others? You can't be serious that
only Abraham would teach his household to follow.
That led into a whole nation following God's guidance to become a purer people than the nations around them from which to bring forth the Messiah.
All the OT says that the Hebrews were
not "purer". The prophets are continually complaining about how impure Israel is. Also, right after God has shown His power in freeing the Hebrews from servitude in Egypt, what do they do? They abandon God and make a false idol -- the golden calf!
Let me submit that you are using "chosen" in an inappropriate fashion. You are looking for qualities in the Hebrews that set them apart from other people.
That isn't the case. God "chooses" the Hebrews in order to demonstrate His existence by intervening in their history. In a very dramatic fashion. Basically, God creates a nation -- Israel -- ex nihilo, out of nothing.
Other nations were in idolatry.
Not at the time. At the time of Exodus and Abraham, the Bible accepts that other gods exist. The Hebrews are simply not to worship them, because Yahweh is their god. It was only after the Babylonian Conquest that we see the new theological idea that there is only one deity -- Yahweh.
Many are called, few are chosen, not because God has favorites, but because only a few pay the price to be chosen. There are requirements. God loves everyone....but has standards by which people and nations experience blessings and or cursings.
This lessens God's love and forgiveness. It also goes against everything Jesus teaches about inclusion. You are being
exclusive.
God chose the Hebrews not because of anything THEY did. The choice was
solely God's to intervene in their history.
And remember, after God "chose" the Hebrews, Jesus ends up disobeying most of the tenets of the faith they had built up over the past 1,500 years.
Also, if you look in the OT, there are several instances where people "disobey" God by arguing with Him. Moses in Exodus and David are good examples. In both cases they get God to change His mind. In Exodus God "repents".

Even Jesus argues with God by asking to be let off the hook in the Garden of Gethsemane.
So, blind and complete obedience is not what God wants.