Let’s suppose for a second that God really told Noah to build a boat and then he flooded the world. I’ll even concede that the animals wouldn’t all kill each other, because everyone knows that animals act differently in a crisis.
Did it ever occur to anyone that God killed a bunch of innocent babies and young children? And what the hell did the animals ever do to deserve being killed as well? And of all things… why try to kill everyone with a flood when anyone with a boat (or sailors and fishermen already on one when the flooding started) would still survive? God is supposedly all powerful… couldn’t He shoot everyone but Noah and his family with lightning, or spread a plague that Noah et al. are immune to, or even just stop their hearts from beating?