We have to start right
In that Noah is ACTUALLY Utnipishtim and his wife was Atrihasa and was most probably an entirely mythical narrative written by the Sumerians
Although…
… if you want to explore potential origins for a flood story, passed down through generations, then I suggest you study the Younger Dryas Period, or the YDP impact
This impact IN HUMAN HISTORY, 12,000BC caused a change in global climate, resulting in accelerated ice formation
In around 10,000BC this ice melt fairly abruptly, a few generations Infact and the oceans rose by some 300 feet
This led to the formation of inland lakes, flooded coasts, flooding of the Bearing Strait, a complete change to coast lines GLOBALLY
IF, this story was passed down through time, of how early humans saw the “ocean swallow up the lands” perhaps this may be the origin of this myth…
OR
It may be a story inspired by the Iraqi flood plain and it’s regular flooding