Generations of people living to be hundreds and hundreds of years old come and go and suddenly there's Noah. At this point God is pissed off about all the fucking going on around him, as well as humankind's violent tendencies, and decides to slaughter every living creature on Earth... except Noah, his family, and around 50,000 animals he's somehow able to get on his boat. Humankind lived on... as I suppose you all know.