Actually, it's not evidence of a major world-wide, life ending flood occurring. Virtually every civilization that has ever survived in this word lived near a major water supply, whether it be a river, lake, or ocean. All civilizations have myths and stories to explain the concept of an angry yet forgiving deity, and since the water supply played a major role in their lives - it is natural for that to be the center of the punishment. If the river or lake flooded or say a tsunami or hurricane hit, it was the norm of the time to consider it a supernatural event.
That being said, however, some scientists/geologists believe only something along the lines of an asteroid impacting could have caused the effects listed in all of the flood stories throughout the civilizations in the world.
Yes, and as was said, those "myths and stories" are perversions of the true account with which their culture was once familiar. The truth degenerated over the years as did their understanding of the true God.