It never really worked.
God knew it wouldn’t I think.
He knew that man would never be able to usher in peace. Regardless of the humans He would put in charge.
Moses struck at God in anger in the wilderness and was unable to enter the promise land.
In Judges there is a vicious cycle of the Israelites doing well, falling into sin, being threatened from other nations, a judge delivering them and then they would go right back to their sinful ways. To top it all off, some of the Judges, who were suppose to be moral leaders still struggled to keep a level of holiness that was needed to keep a nation on track with God.
In “Kings” they replace God as their King with a human king. A king that failed and had to be replaced. Then the next king had a moral failure but got back on track. However, his son who took over started well but then went off the reservation by worshiping other gods and marrying too many women. After his reign the nation split in two (one north and one south of course). Both wind up being exiled to a foreign land as a judgement because of their lack of resolve to follow God the way they should.
It seems that mankind just can’t get it together and the “people” God chose to bring the nations back to God struggle keeping the 10 commandments and other requirements for them to be a holy nation. They just can’t make it to Holiness.
History shows time and time again that mankind can’t save itself.
This is why God made promises to us that He would come and rescue us. The people who can’t rescue themselves needed a rescuer from the outside.
Someone outside of humanity that would become “flesh and bone” to save them.
God promised them that very miracle would happen one day.