Since you asked... let's just boil this down a bit...
The only reason Israel exists as a state is because post-WWII nobody wanted a mass influx of Jewish refugees in their country. Full stop. The US, for instance, famously rejected Jewish refugees fleeing the Nazis, a lot of whom had to return to Nazi Germany and die in the Holocaust.
After the war, a lot of Jewish people had no place to go... and countries like the US and Britain didn't want them all living there. We can be as pro-Israel as you want, but the honest truth is at least the people in power in those countries that are pro-Israel do NOT want them all coming to their countries to settle in. Make of that what you will.
So... the US and Britain primarily... decided to make a Jewish state in the middle east. You know their "promised land" or whatever. Jewish people who hadn't been back there for generations, whether they originally left willingly or not, were encouraged to move back. But the problem was... lots of Arabic people, many muslim, were living there and had been for quite a while. Land was taken away, sometimes quite arbitrarily, to make room for the influx of Jewish people. Even land that was bought, it was kind of like imminent domain where the government comes and forces you to sell some or all of your land and they name the price and you pretty much have to accept "or else."
There was never really a chance at a Palestine with this mindset. Also, each group had legitimate claims to some areas in terms of historical or religious significance to them, and neither side wanted to fully share. That said, Israel has had a lot of Palestinians living there in peace and many citizens of Israel do not at all support what their government is doing.
In the beginning, there was some expected backlash from Arabs who felt like they were being run out of their homes and land unfairly. Nobody took their side, often not even surrounding Arab nations. Israel had US and Britain backing from the beginning. And while it is true as far as I'm aware that the first violence in the form of war/attacks came from Arabs against the Jewish people... can you truly blame them?
Everyone who supports Israel goes with the "they were there first so it is their land" theory... except... nobody applies that unilaterally. How about the US... remember those "Native Americans" who had pretty much everything stolen from them? They were here first... Imagine if Russia or China loads up and comes to the US one day and says, this country really should belong to those Natives... so we're going to take most of the land and give it to them, and you other Americans need to fuck off on whatever land we deem fit for now until we decide to take that from you later too.
Can you imagine that going over well here? I can't. But it would be just as fair.
Or even just immigration... the US right now has a hard-on for wanting to expel illegal immigrants... "it's an invasion" or whatever... you know, kind of like when all those Jewish refugees from Germany who wanted a better life "invaded" the middle east... But fuck remembering history... When it happens to you, the immigrants are bad and must be repelled... when you're the one sending them somewhere else, then you want them to be welcomed.
Are there terrorists in the middle east doing horrible shit? Yep. Are many of them Arabs or Palestinians. Sure. I won't defend the horrible. But I will say... see what happens if someone comes to take your home and land away... see what you do... especially if you feel like your friends aren't helping to defend you and you're on your own... you might get proactive too. It's not great, but it's life.
There had to be a half dozen or more BETTER ways to take care of the Jewish refugees post-WWII... but the truth that I started with was, the major powers didn't want them in their country. If they did, we'd be in a different world right now. Instead, the powers that be after the war cared less about Jewish refugees and more about keeping them out of their back yards... and said "here, you guys figure it out over here."
I could go on...