Palestine was part of the Ottoman Empire who fought alongside the Germans in WW1. The Ottoman empire lost and was dissolved(you keep bringing up a defeated Germany). Britain's conquest of that area gave them Authority to return the Jewish to their rightful homes.
It was already a huge hub of multicultural immigration because the Ottoman's declared it so and sold huge parts of land to the Jewish between 1850 and the early 1900's for cold hard cash for the Empire, knowing the jewish had been resettling and being wiped out there for millenia due to it being their ancestral home and the seat of their religion.. The Jewish residents proved very able to help the Economy there and did so well they were able to buy and buy more land and more and more folks immigrated there. Essentially it was their Statue of Liberty calling "Bring me your tired your hungry your poor". Its said that the ottoman's actually feared the rising jewish economic power more than they wanted their taxes and that combined with fears that the jewish may help their WW1 enemies (that's us). That's why they eventually just kept all the money they made from them and evicted, deported and killed them.
All Britain did was correct that wrong after they took over that patch of the Ottoman Empire. All this happened well before WW2 was even a worry.
It also became a bastion of hope for Jews fleeing Germany and Hitler's rise to power yes. Amidst all the attacks on the jewish even when there were far fewer of them before they had any power. The Arab riots and anti semetic racial hate happened well before the jewish even had a minor militia. it was the realization of how it was going to keep happening and the ultrareligious hate of the Arabs that hardened Israeli's into what they are today.
Why after living there legally for decades since the Balfour declaration in the 20's would they suddenly abandon everything they built to go to Germany? That's like telling American Settlers to leave the land of opportunity and go back to Europe after 30 years for a lot of them.
Your Scenario makes no sense because all these things were decided before there was even a WW2. And it is weird that you think it would have been some stroke of genius.