Thanks Tam. I appreciate your input.It can be that at some point in time, there are going to be huge flood events caused by climate change or shifts. But because there might be a great flood myth in one mythology does not mean it is the same flood myth shared with other cultures.
It is like with modern times, you can have separate cataclysmic floods that happened in Australia, then in Texas, and then in Southern China. It doesn't mean there is one huge global cataclysmic flood that happened all the way from Southern China to Texas. You can have simultaneous and parallel great flood events happening across the world in a span of years, with leaders of tribes leading their tribes out to safety, and these parallel stories passed on from generation to generation, but it does not mean there is only one leader and one tribe of humanity. Ancient people often tend to portray themselves as the only Ones, unaware of the existence of other cultures on Earth because of the obvious lack of global communication.
So for me, Noah is probably someone who lived in the Fertile Crescent, currently in Iraq. There might have been massive flooding that forced him and his group to move upstream, maybe to southern Turkey, due to the constant floods and rainfall. What started as a simple survival story ended up being a legend, then a myth, then part of a religion.
Yu could simply be one who lived in the Yellow River or Yangtze, where cataclysmic river flooding happens regularly. Maybe one day, the regular event turned extra ordinary, and he could have led his own people to flee and find safety. After all, that's what people should do. Today, we would call these people heroes, and that's how legends, and ultimately myths started. This is a kind of event that can happen in the Nile, or the Ganges, or in the Amazon River, or in any coast. There are modern day floods that looked and felt Biblical in scale and it might feel like the end of the world, Judgement has come, the Revelations is being fulfilled, for these people.