And people living thousands of years before the Incarnation have exactly what to do with the question?
Jesus was a Jew, whether you take that word in the strict (of the tribe of Judah) or broad (Israelite) sense. His disciples and later His apostles were all Jews of the twelve tribes. He lived under the Torah and fulfilled every requirement, and even said heaven and earth would pass away before the Old Testament.
Salvation is not by keeping the Law, and never was, but by faith in God's provision in Jesus Christ alone. Christ fulfilled the sacrifices of Israel. But that doesn't mean that He did away with Israel as a nation, nor that He has cast them off forever in favor of the Gentiles, as all the prophets and all the apostles make very clear. We are grafted into Israel's root, but we have no cause to glory over the natural branches (Romans 11).
Exactly!
"His disciples and later His apostles were all Jews of the twelve tribes."
You need to get back to Scripture for this one. It is error. The only son of Judah among his apostles was Judas.
All of the other apostles were of Benjamin, even Paul.