These are all current beliefs, sort of like beliefs in the Middle Ages that marriage was only between a man and a woman. Animals rape children all the time. They also kill the children of rivals without remorse.
I know of many animals that will take in other mothers babies as there own, & elephants who go to great lengths to protect eachothers offspring & show affection.
As for animals raping young offspring, do you think animals have the brain capacity of humans to know any better?
Are you comparing mohammed to these animals? because he seemed not to have the brain capacity to know any better either.