Prudie, I believe most of the deceased are people who got between a hippo and his water hole: they get agitated and stomp anyone who gets in their way. They're vegetarians.
I know they are cute looking and mainly herbivores however the killing of humans appears to be mainly deliberate, not accidentally stepping on those in the way. They clearly don't like us as much we like them.
I agree and love all animals and would forgive them nearly everything they do, including hippos who kill humans. I'm just making the point that they are very dangerous. They don't accidentally trample people in their way, they deliberately attack people, especially in boats and bite them. Look it up if you don't believe me.