I have a genuine question

I apologize in advance for how dumb this question might be. I’m trying to learn more about Israel and Palestine and there’s something that I haven’t been able to figure out and it’s making me feel dumb. I’m asking this genuinely and it’s not meant to be rhetorical or inflammatory at all.

If Israelis have all settled in Israel and it was never their land to begin with, where are they supposed to be/live? During and after the Holocaust, were the Jews given a certain piece of land, but since then they have tried to take more than what is rightfully theirs? I know this is extremely complicated but I feel like I can’t understand the whole situation without understanding this part of it. It seems like people are taking issue with Israel “defending itself” because it’s defending land that isn’t or shouldn’t be theirs. But where are the Israelis supposed to be if not Israel? I know this comes off as extremely ignorant, but I have been thinking about it a lot and I’m trying to learn as much as I can. Thank you!

Edit: Thank for this information! This has been on my mind for a few days now. One of my best friends is Jewish and lives in Tel Aviv and I know she wants to discuss these things with me (she hates Bibi). This context is helpful.