Fermi paradox, great filter, we all go through them all the time at every level, the filters are in place to allow us to evolve. The great flood as a thought experiment – if we’re all going through great filters it will only be the ones most suited to survive who survive. If there was land life that existed pre-flood, then someone clearly survived the filter. In the case of christianity’s “Noah”, maybe it wasn’t necessarily that he was told by god to do something, merely that he was the first and only person of his time to attempt building a new method of survival… a large boat with provisions. Survival instincts are what cause things to make it past these filters. This happens on every level. Cells die because they are too weak or wounded to continue reproducing themselves while cancer has found a means to survive the killing filters at this level.

Parables as logical thought experiments