Time for you to mature in your faith. I suggest taking a bible class in your local parish, if they offer one.
If God preserves a remnant of the nation of Israel today, which he does in the Church, the Jews(Israel) are still God’s people. See Romans 9,10, 11.
Greater Israel has been hardened so that the gentiles may come in, the wild shoots can be grafted into the promises given to Israel. St.Paul teaches that the Gentiles in the Church should boast over the broken branches of Israel, because if God did not spare the broken branches, he will not spare them either(Romans 11). Israel is now disobedient, like the gentiles, which means that God may show mercy to them all.
Also, not “all” gentiles believe in Christ.
You keep focusing on the Jews in Jerusalem that had to do with Jesus crucifixtion. Why don’t you also show the same focus of the hundred’s of Jews in Jerusalem that shouted-“Hosanna-blessed is he who comes in the name of the Lord”. The next time your at a Palm Sunday Mass, and you are holding your palm branch, look around at everyone else doing the same. You are recreating what Jews did for our Lord some 2000 years ago!!!