There is a lot about these Old Testament stories that we simply cannot understand since we weren't there and event he writer .......wasn't there. I enjoy reading your thoughts because they are very similar to thoughts I have always had.I'm thinking all these events fit together. I'm looking at the texts and the various sciences... I'm not hung up on some ridiculous "young earth" concept, that was never much more than poor scholarship. The planet is still coming out of the dark ages, but we are starting to piece the puzzle pieces together. Genesis is one piece of that puzzle.
You know what strikes me, when I read Genesis? The way God just lays out what to do, as if it was no sweat... and Noah knocks it out, with no complaints. In reality, this could have been a plan of action for the entire region of the world where Noah lived, and the story might very well have originally intended that only the people who built arks survived the flood that walloped that area. The story is told in past tense.