I liken it to the story of Noah. Whether that was the mediterranean re-joining the Atlantic and thus oral re-tellings from a much much earlier event or merely a localized flood you can certainly imagine someone preparing for a flood and surviving localized or wide-spread destruction. But two of every animal? That's not a stable genetic population. Hell there are 40,000 or more species of spiders! There is simply no possibility that you could even fit enough animals on a boat of any kind to make that story work. If it did happen the immediate result would be complete genetic collapse and extinction. The idea is abject nonsense but the core story probably happened.

It is easy to imagine a large group of slaves escaping or being freed from Egypt. Maybe they or their ancestors were war captives. But wandering the desert for 40 years? Yeah right. Even if you want to grant miracles the idea that all of Egypt would even know about such events at that time is bananas. Information didn't travel that fast. Probably one group of people in one city. And the antagonist could easily have been a local lord. Over time it became the Pharaoh and the 18 months of wandering turned into 40 years. Only then it was written down.