Ahh little do most know and recognize the bible uses alot of the mythology of what the people considered then to be true to teach a spiritual lesson.
Its the same as the legends of greek mythology, it came out of the imagination of someone and it came from a book a person wrote. If you want to consider leprechauns existence, you then can consider all the other stuff written from the imaginations of authors of books. Think about what came out of the imaginations of the people who do the dungeon and dragons books and games, whew.
There is a large, truck sized hole in your argument.
The bibles, neither the OT or NT, are merely "teaching tools".
They quite clearly lay out and define not only their respective and subjective moral sets and laws, they create what I will have to, in all honesty but still grudgingly, admit is a Theopolitical Manifesto of a superb caliber, one that is effective even in this modern age in western society.
The myths contained within, especially the Creation, Adam and Eve, Flood/Noah, and Job myths are intended solely to put an ultimate authority in Jehovah, and through that deity, supreme power, control, and authority of the clergy of the related religions. The scriptures also specifically target competing religions as well, relegating them to some "primitive ignorance" that must be stamped out and corrected, and those poor innocent devil worshiping heathens corrected at any cost.