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.
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