1) What about micro-organisms which breed asexually? Did they go in two by two? Or just one by one?
2) What about fleas and ticks? Did they ensure only two of each species of parasite went on board?
3) What about wood-boring insects and woodpeckers? I bet they were a bit of a pain. Though if there were only two of each, then maybe not!
4) What about plants? Two giant redwood trees maybe?
5) What about aquatic life? Specifically freshwater life. Did Noah invent fishtanks?
6) And what did the carnivores eat?
Of course the whole thing is nonsense. Equally there were undoubtably disasters on a local or wider level which would have been handed down verbally or in writing over the centuries and used as the allegorical basis of Biblical and other stories.