But as you say, you are one family.
That is precisely what Paul says in Eph 2 and 3 and in Gal. 3,4 and in II Cor. 3 and in Acts 13.
Furthermore, Ezekiel 16 makes very clear that Israel was ADOPTED, not birthed by God, else he would commit incest by marrying her. "the Ammorite was thy father, and thy mother was a Hittite." God found her as an abandoned infant left to die.
Furthermore John 3 makes very clear that believers are born from above, by the Spirit.
Apparently Israel is adopted and the church is birthed.
In Phil 3 Paul lists all the advantages of Jewish birth and faith but then claims that he considers them manure for the sake of the excellency of the knowledge of Christ. Now why would Paul, Peter and other Jews abandon the superior blessings of belonging to OT Israel for the inferior blessings of belonging to the church?
According to your analogy Paul certainly was grossly wrong in Phil. 3 as well as the other passages listed above.