This is a rewrite of my comment as more of an argument and less links and speculation, since I think that parts of it might be clearer that way.
Lorenz’s theory is that humans evolved to respond with an awwww to the features that distinguish infants from adults, and so we also awwww to other animals that have those features. Why do other species have features that we find cute? One reason is that we’ve exerted selection pressure on them—for instance, by being more friendly to cuter wolf/dogs. A second is that features common among mammal young naturally became features of human babies, so of course other baby animals have some cute-inducing features. A third is that features that differ between babies and adults also tend to differ between different species, and so there will be some species that have the baby-like version of those features or even a more extreme version. Babies are smaller than adults but some species are smaller; babies have small less-protruding noses but some species have smaller noses; babies have small limbs relative to their body but other species have smaller ones; babies are soft but some species are softer.
Bunny superiority may just be a result of there being enough species so that some will have a large enough collection of extreme cute-inducing features to be super-adorable. And since our ancestors don’t seem to have wasted a ton of fitness on cute non-humans, they didn’t undergo a strong evolutionary force to prevent the bunny takeover.
This is a rewrite of my comment as more of an argument and less links and speculation, since I think that parts of it might be clearer that way.
Lorenz’s theory is that humans evolved to respond with an awwww to the features that distinguish infants from adults, and so we also awwww to other animals that have those features. Why do other species have features that we find cute? One reason is that we’ve exerted selection pressure on them—for instance, by being more friendly to cuter wolf/dogs. A second is that features common among mammal young naturally became features of human babies, so of course other baby animals have some cute-inducing features. A third is that features that differ between babies and adults also tend to differ between different species, and so there will be some species that have the baby-like version of those features or even a more extreme version. Babies are smaller than adults but some species are smaller; babies have small less-protruding noses but some species have smaller noses; babies have small limbs relative to their body but other species have smaller ones; babies are soft but some species are softer.
Bunny superiority may just be a result of there being enough species so that some will have a large enough collection of extreme cute-inducing features to be super-adorable. And since our ancestors don’t seem to have wasted a ton of fitness on cute non-humans, they didn’t undergo a strong evolutionary force to prevent the bunny takeover.