Imo the whole "let's give Jewish people a state after the holocaust" thing was a good idea, but they should have put it Germany. Germany were the ones who actually Did the holocaust, therefore there's some argument to be made that they were entitled to German land, you could consider it a form of reparations. There was no argument for Jewish people being entitled to Palestine because their ancient ancestors lived there like 1800 years ago or whatever

the settlement started before British support which came later. It's super complicated.

edit: reasonable overview on Wikipedia of events leading up to Israel actually https://en.m.wikipedia.org/wiki/Zionism

Bastardised simple summary is

• Europeans treat Jewish people like shit for thousands of years
• creates support for Jewish sovern state
• languishes a while but antisemitism gets worse
• in typical European fashion it is decided to just start settling where other people already live and force the existence of a country
• ww1, Britain and France decide they know how to do a middle east. Results show typical commitment to stability and fairness.
• settlement is supported by various and sundry European powers inc German Reich in lead up to and during ww2 because everyone hates Jewish people and wants to foist them off to some other, preferable brown skinned, person's country.
• after ww2 everyone eventually gets mad at the results of this sensitive and thoughtful plan, including European supporters, neighbouring countries, Palestinans, and many Jewish people. Fear and hatred fuel dominance of increasingly aggressive right wing political parties.
• everyone except the USA that is. Their government has a blast supply weapons after Britain and France wash their hands and claim guiltlessness.
• land grabs and oppression intensifies