Because you see all Jews as from Palestine. That isn’t the case. Before the colonization project started Jews and Arabs had lived together there for thousands of years. Then Europeans showed up, and suddenly most of the Arabs are corraled into reservations that the Europeans and Americans keep encroaching on with settlements.
Rather than assimilate to the existing culture and produce a single post colonial state they decided to try and push the Arabs out. Nobody would care if they had produced a post colonial state that had heavy protections for Jewish refugees, but was not a Jewish state.