I dont want to talk on Religions in this forum but ...
I dont think Zorostrianism came before Jews.... Jews already exist before 6th century B C.it was their second temple time there were dead sea scrolls from that time. "Fundamentally the Jews were polytheists" You decided already went back in timemachine. Jews did worship other g_ds in the middle but their fore father did not...they were monotheists just because you see many similarities with Jews in Zorostrianism and you claim that Zorostrianism existed before Judaism Even Islam calims so ....