There is another option with Noach, for those who really like to think that Noach actually existed. I suppose you could say there was someone called Noach, who was miraculously saved from a devastating flood by God. Why is the Torah interested in the story of Noach? I guess because he was the ancestor of Avraham. Or maybe for some other lessons.
Of course to fit with science, the drama of the whole Noach story is totally gone. It was just a flood like many others, many survived and many did not. Plus there probably were not many animals on the boat, unless he had his pets and maybe some livestock with him. Probably also was a very very small boat, not something with more square footage than a Nimitz Class Aircraft carrier. Also the 120 years worth of building is not likely, considering that nobody in those days lived much past 70.
According to this interpretation, you get to keep Noach as a real person. However you have to say that the Torah totally exaggerated the story beyond all proportions. Which is worse? Saying the Torah contains mythology to teach some ethical lessons, or saying the Torah contains exaggerated stories?
According to the Mahartzu (as quoted by R Gil), there is an opinion that Breishis was actually written by the Avos (and Noach and whomever) and then included into the Torah by God (or Moshe on command of God). So I guess you can say that Noach was guilty of the exaggeration. And maybe we shouldn’t really blame him, because from Noach’s perspective, you can imagine things looked pretty bad. Maybe he was suffering from Post Traumatic Stress Disorder?
But if God knew the whole story was an exaggeration, caused by Noach’s PTSD, why didn’t He edit it out? I guess the answer is obvious – How can you question the mind of God?
And if you believe any of that, I have a furry lemur here who has something very important to tell you.