it does seem a bit odd that god wiped out all those people for no reason, as (if noah and his family were the only human survivors left) judaism (as christianity then was) was never the dominant religion even after the flood.
Surely if the only couple of people left after the flood were people who had been saved by god then judaism might have been the dominant religion for a week or two.
Also, surely the comment about "2 sources of light in the heavens" proves (more so than evolution or anything) that the bible isn't what actually happened, but stories to allow more primitive people to understand the broader concepts. We know that the moon doesn't emit light.
THis doesn't make the message of the bible false, it just means that every single tiny (mistranslated, passed down) wprd houldn't be taken as the litteral truth.