To me, the purpose of God separating a people unto Himself ( by choosing Abraham and granting revelation to his progeny through Isaac – the rest of the Old Testament ), was not to keep people separate centuries later, but to establish a hierarchy of humanity based on noble examples, not power.
Much how a noble family stays 'noble' by their virtues, their words AND their actions, so does a righteous person show themselves to be 'right' ( by their words AND deeds ).
In due time, we can see how societies both big and small ( empires and still existing indigenous tribal families ) reflect much of what God started. We can read how their lives reflect the premise found in the law of Moses.
This was to bring unity among all peoples, not division. People are divided by their projected ideas.
Identity plays a big part in dividing people. One says they are a Jew, another an American, another a Muslim, another a ____ ( fill in your identity ). But, before and after all this, we are human beings. Even science is now discovering we are all related. So, in essence, we are brothers and distant cousins. This reality is evident when people put their exterior differences aside and focus on the similarities. This, God has purposed. But folks, out of pride or programming, fall into their identity traps, following terms, labels, titles, etc. Do these truly define a person, a human being, a child of God?
Before your identity, are you not a human being?
We could look past the words made for us to conceive our differences, or we can see what God has done in bringing all people into one community. This has been both the aim of men and apparently the will of God!