Israel has worked tirelessly and VERY intentionally for decades to put Palestine into the vulnerable position that it's in. This was always the goal.
They don't have an independent state. They are an occupied territory whose lives and economy are controlled by the Israeli government. This is important, because if you're a Palestinian activist, they could arrest or harass you or your family at any time if they don't like what you're saying. Palestinians cannot even travel or immigrate outside of Palestine because they are considered "stateless" due to Israelis work towards getting the international community not recognizing them as a state or their claim over land. Meanwhile, Israelis are free to travel internationally to schmooze with any leader they can.
They do not have a standing army--indispensable when you want to defend yourself from genocidal attack like this and the world won't come to your aid. PMs of Israel have specifically stated it would be unacceptable to allow a Palestine with a standing army.
They have isolated Palestine from having global, political relationships and allyships, which would kick into affect, like how America is defending Taiwan because of its semiconductors. America has AIPAC, their cabinet members filled with Israelis/Jews who lean heavily on leadership. Similar with Britain, Europe. The International Criminal Court is in their pocket, as evidence by their biased way of ignoring all Israeli war crimes while going after Russia. (By the way, how fucked up has Israel made the world, turning what was supposed to be an objective moral institution into a political institution).
It's unpopular and unconscionable to support Palestine. You don't have political dinners with large groups of Palestinians. Political leaders will not meet with you. They have recently prevented Palestinian leaders from speaking in America.
On top of that: Public perception. The media was long ago bought and paid for. Framing Palestinians as terrorists, bad guys, dehumanizing them, justifying actions. Providing sound bites that incorrectly represent the situation. "Israel must have self-defense" "They'll kills us" "Only democracy" "Most moral army". etc. etc. etc.
Silencing Palestinian voices in any way they can. Shutting down art exhibits, documentaries, speakers.
If nothing else, desperate harassment, meltdowns, and other abusive methods meant to invoke "fight or flight" response to pressure people into agree with them.
Finally, culturally the racism that Israeli children are indoctrinated with (and the generally genetic lack of empathy) prep them for genocide. Israelis are prepared to dehumanize Palestinian children, destroy and steal their homes, and participate in the ethnic cleansing. 80% support this cleansing. The hatred is in them.
They are raised to have no greater respect for children/pregnant mothers than the slave drivers who threw black babies to alligators.
How could the world have moved to stop this?
This was all intentional and speaks to their murderous ambitions in the region. They have framed themselves as "good guys who just want to live in peace" while they are the most conniving people out there with huge political aspirations. Saying they just want to live ignores the fact that Israelis do HAVE goals, which always included removing Palestinians.
LYING and trying assuage leaders that "they aren't going to do a genocide" just long enough to successfully turn around and DO that exact thing, letting the leaders know they got screwed and lied to.
Blaming Palestinians for the continual loss of their land and rights because they acted as "savages" is wrong. No amount of Palestinian peace would ever stop Israeli aggression and ambition. It's wrong to assume that Palestinians could have done something to stop this by doing nothing. Attempting to resist only sped it up, with a flimsy justification, but the suffocation was always coming. "Let me kill you now, and if you struggle I'll kill even more of your family through collective punishment."
In fact, Palestinians have just been trying to live their lives, as best as possible with the daily violence, harassment, discrimination, and humiliation, hoping it would be enough and it was NOT. The West Banks hopes it will avoid this fate by not being terrorists, but they will not. They should have realized the existential threat living next to them. Israelis have always been a snake in the grass, from the moment the Palestinians opened their homes up to the Jewish WW2 refugees who turned around and spoke gleefully behind their back of how they'd planned to rob their kind host.