I apologize if I misunderstood you, but it seems to me you were saying both that the Torah and the other stories had a common source, and that the Mabbul was a local event.
Anytime one is discussing HaShem or the Torah, it is best to be as precise as possible. Casual Internet parlance can lead to all sorts of assumptions by readers.
“and that the Mabbul was a local event”
Now, this, I did say is possible. I recently attended a lecture at Chabad that discussed the texts and authorities on this issue that was very persuasive.
Briefly, “kol erets” is used a number of ways in the Torah, which can mean “all the populated world” or “the entire globe” or even more limited to a specific area (as when discussing certain leaders who were king of the “whole world” when we know them not to have been).
Not clear at all, and you have to look to oral tradition, which is also not particularly specific on the issue.
Again, not advocating any given position, but I will state that the Orthodox world is not nearly entrenched on the concept of a global flood as one would think.