Hmmm...looks like you are ignoring this fact... Certain individuals disobeyed the truth and veered toward foreign religions as they do in any age; however the Israelite religion itself was monotheistic back to Abraham.
I imagine some ignored Zoroastrianism and continued to worship false gods. Yet Zoroastrianism itself wasn't polytheistic. Same thing.
Well,perhaps.
The difference is we have written proof that Zorastrianism goes back before Moses.
With the Bible we have written tradition. I don;t know when the Hebrews developed writing. The question is, did it predate Avestan? If it didn’t the Biblical writings were oral testaments before they consigned to writing.
From a theological perspective, as a Christian, I wan to believe that there was an unbroken tradition of montheism going back to Adam. But the Old Testament doesn’t appear to emphasize angels to the extent Zorastrianism does, and I believe the concept of a life after death, a final judgment, a resurrection of the dead, the idea of the world as the site of a cosmic battle between good and evil, etc, doesn;t appear to make itself evident until some time after Moses, most probably after the Babylonian captivity. Even today, I don;t think most Jews believe in a life after death, a final judgement or a resurrection of the dead. That is only found in Zorastrianism and Christianity, although there may have been Jewish sects in Biblical times which believed this.