Answer:
Hey there!
Pretty early on in the story, one can know this is just a myth, and not actually something that happened in real life. For example, the first sentence says, "In the beginning there was no world, no land, no creatures of the kind that are around us now, and there were no men." We know that scientifically, we can prove that in the beginning there was in fact a world, land that wasn't built by a person, and there were creatures (humans) like there are now.
Let me know if this helps :)