Young animals don't generally reach optimal cuteness until some time after birth. Given the slower rate at which human young mature relative to other animals your cuteness sense for humans is not necessarily inconsistent with the normal response to animals. It seems to me that the pictures used for comparison in the OP use a bunny at a relatively later stage of development than the human infant.

Newborn puppies, kittens and rabbits are peculiar little blind wriggling things and are less cute than slightly older young animals. Newborn rabbits appear to be hairless.