> faithful to the actual historical event

What event?

I understand you saying that a flood actually happened, and that Noah's story is based on that. Well that may be, but with a quibble: that flood is prehistorical. We have no records to say when and where it happened. Unless I'm behind on research.

To me, flood stories serve to show how powerful gods are. The stories are likely based on several floods experienced by different people over time.

Imagine you see the Nile flood your general area every year with varying intensity. It's easy to worry that one year it just won't stop rising. To people living in those times, a flood story is gripping in ways we don't follow today.