Elephants are passive creatures. They are strong, but slow. Pig Peter mentioned this creature in an interview in April. It won't be an aggressive creature. It's totally passive.
Pigs are slow, but quite strong.
Lionhead isn't sure yet, if the pig will find it's way into the final game. I could imagine them being like apes. Maybe a little bit faster and weaker. Human Peter already said in an interview that there won't be a Human creature. After that there really haven't been any screenshots of the Human creature, but as a christmas present we got a shot where a human male is fighting.