Then why would God bother to separate Abram from the rest of the heathen world, change his name to Abraham and give to him His covenant promise, for a specific people that God formed to be His nation of priests, in a specific land? That doesn’t make any sense. The Abrahamic Covenant was established by God to a specific nation: Israel. Not the whole world. Meanwhile, what were the Gentile nations promised? Anything? The same thing Israel was promised? Both? Neither?
God made a difference between Abraham and the Gentiles when He gave Abraham a wall of partition between him and the Gentiles. Circumcision. When Abraham was 99 years old. That was God’s sign that they were to be a separate people from the Gentiles. With a separate land, separate duties, and a covenant promise with him that God would dwell with them in that land, on this earth one day.
There are many things going on here - But I think the general answer to your question is that YHWH talks to us with pictures. All of national Israel is a shadow picture - a miniature in a box, as it were, of what will eventually be, in terms simple enough to digest - Think crayons here.
To be simplistic, The Temple is God, the priests serve him, and minister to the general population.
The end result, when it is finished, God is God, all of Israel are the priests that serve him, and minister to the whole world as the population. The Order of Melchizedek is the setup for that.
The Abrahamic Covenant was established by God to a specific nation: Israel. Not the whole world. Meanwhile, what were the Gentile nations promised? Anything? The same thing Israel was promised? Both? Neither?
Do not forget that the main purpose is to save the Sons of Adam, not Jacob - Israel was the first-stage roll-out. The Christians are the second-stage. I think the Kingdom is the final high-production stage.
You seem to see the mystery of YHWH as a sudden revelation, I see it being rolled out, all the way along.