Good questions.....
God did not choose Israel because they were a superior race of people....good grief!....he wanted to exterminate them at times because they could never do as they were told. But there was a reason why he chose just one small nation to make an example of....both in a positive and a negative way. It was a teaching exercise as well as a means to send his son in to the world with clear identification.
Abraham was the most righteous man in the world at the time, so he made a promise to him that through his offspring, the Savior would come.....in a specific tribe, at a specific location, and at a specific time, so that his people would be able to identify him.....but they didn't want him because he did not fulfill their false expectations, and hence, they made excuses to do away with him (as they had done to God's prophets previously.) But through his interactions with this nation, and their obligation to keep his laws (given to no other people) he provided a record so that future generations could see what was required of them, and in turn, what he would do for them if they followed his instructions.....and what would happen if they failed.
There was no point at that time because he was making history with this one nation and creating precedents for his future worshippers who would come out of all nations as he had promised Abraham in the beginning.
Those outside of that nation were virtually left to their own devices and gods as they lived and died for the thousands of years that have intervened. Since the Bible teaches that all who have died are still in their graves, he has promised a resurrection to all of them, no matter what gods they worshipped in their ignorance. Knowledge is what obligates one to worship the true God. If you don't know him, you can't worship him. If you are unaware of something then your actions are not deliberate. No ignorant person will pay for their sin. Jesus did it for them......but there will be obligation on all who become aware of their obligation after their resurrection, but who fail to fulfill it for whatever reason.
His original promise to Abraham was.....(Genesis 22:17-18)
"I will surely bless you and I will surely multiply your offspring like the stars of the heavens and like the grains of sand on the seashore, and your offspring will take possession of the gate of his enemies. 18 And by means of your offspring all nations of the earth will obtain a blessing for themselves because you have listened to my voice.’”
So the family who came from Abraham's grandson Jacob, were going to become this great nation whom God would protect and bless as long as they obeyed his commands. No enemy would be able to defeat them in the name of its god, because Israel's God was superior. Time and again, he demonstrated this. But when Israel rebelled and disobeyed their God, he allowed their enemies to wipe the floor with them.
It was going to be at the time when this object lesson was nearing completion that he would cleanse a people out of all nations and have them declare the good news of his incoming Kingdom which will destroy all failed human rulership, and replace them with the rulership that humans should have had in the beginning.....the one we have never had the pleasure of enjoying. They threw that away in favor of ruling themselves, and we have been reaping the consequences ever since.....I don't think that most people have any idea what we lost.....
Instead of this.......................................................we have this.
God will take his planet back and reward those who never lost faith in him....that is what I believe....
God's Kingdom will "come" and only then will we see God's will "done on earth as it is in heaven" ....that is how the Bible explains it to me.