Much of ancient jewish lore was a redaction of earlier Mesopotamian mythology (Sumerian, Akkadian, Assyrian, and Babylonian). Why are these earlier stories, of a different Noah, a different Cain and Abel, et.al.; merely mythology; but the redaction by the Judaens and Israelis and Egyptians are the holy word of God?
I don’t know who told you that story or why you believe it, but with about an hour’s worth of legitimate research you could see that it’s a figment of someone’s imagination. The sorry thing is that you’re betting your eternity that it’s true.
Jesus fulfilled hundreds of prophecies in His first coming. All were a matter of public record at least 150 years before His birth. There is no standard of measure you can use that would permit attributing that to coincidence. The only explanation possible is that someone who knew the end from the beginning told His people what would happen in advance. That’s how God has authenticated Himself to man from the very beginning. It’s called prophecy and the Bible is full of it.
But the simple truth is that if you’re right when I die I’ll just be dead. But if I’m right when you die your problems with God will just be starting. If you’re OK taking that chance then so am I.
The answer to your question is that people have been making up stories about our origins since the beginning of time to avoid having to admit there’s Someone they’re accountable to for their lives. Mythologies are corruptions of God’s word, not the other way around.