To put it simply: Jewish people found out the hard way what happens to people who don't have a nation-state to represent and protect them. International politics is fucking brutal, and without an army you are mostly helpless to prevent larger states from trampling all over you. Indigenous people all over the world have been genocided just because they were living on a piece of land too valuable to somebody else, so after the Shoah the world thought that giving the Jewish people a state would protect them. Now Israel's actual formation is much more complicated since only a select minority of Jews were part of that specific project but that's the basics.
The issue now is that Israel became one of those strong nation-states that trample all over weaker defenceless people. Now Palestinians are the (functionally) stateless ones that are stripped of their basic human rights for being born in the wrong place. The core problem of ultimate state sovereignty leading to ethnic cleansing still remains, just the targets have shifted over time as peoples move up and down the geopolitical ladder.
TLDR: "what if we just gave the Jews their own ethnostate? then if they keep getting killed no one can blame us anymore because they would be in charge of their own security" - UN post-war trying to solve fascism while nearly blacking out from liberalism