Leviticus 11:45 states that God is the Lord who brought His people, the descendants of Jacob out of the land of Egypt. I think right now God chose this group after promising Abraham that He would create a nation of believers based on Abraham's faith, who is an ancestor of Jacob. God then commands His people to be holy because that's pretty much God's standards!
God also addressed non-Jews back in the time of Moses, and He allowed those foreigners to be a full part of God's people. Some believers are stating that God no longer has a heart for the Jews, which has been accused of being anti-Semitic, because the tribes of Israel kept on disobeying God. There are examples in the Bible where ordinary people were very stubborn and God was able to change their hearts, like Jonah who was swallowed by a whale and forced to live in there for around a few days. It's an interesting story, and I wonder if it sounds so far-fetched some people would just consider it a myth. If God is able to change people's hearts, I think God still has a heart for His originally, intended people only because of the promise that God had made with Abraham. The New Testament does talk about God wanting the gospel to also spread to the Gentiles, but they were around in the Old Testament, too. All because of Jesus dying on the cross, God is allowing any believer to become a child of God.