A cognitive module for cuteness only needs to make us find babies a nice thing and enhance the probability of parental care. It simply doesn’t matter if, besides doing that, the same cognitive module make us find bunnies or orthorhombic sulfur crystals at low temperature cute, so long this doesn’t have any deleterious effects. Probably a cognitive module that can find cute only human babies and not bunnies is more evolutionary improbable and developmental costly having the same relevant behavioral results of a more cheap and universal cognitive module for cuteness. Evolution only needs to shape cognition in order to generate, more or less, the right type of behavior. It DOESN’T have to, and in most cases it doesn’t, shape cognition nicely, in a way we would look at it and say “nice work”.