Look, I'm gonna say it so nobody else has to: people like to watch animals fight. Man vs Man is the most common of our movie going experiences, but the wide world out there in real life pits man against beast, chicken versus chicken, dog versus dog, and tortoise versus hare. With Rampage, we see a full acknowledgement of this with The Rock versus Flying Porcupine Wolf, Warthog Alligator, and Big Ape.