Here, the Croods are hunted by a big cat-like species. In the Paleolithic Age, humans were constantly preyed upon by saber-toothed tigers, which were a species of big cat.
Eep blows into a horn, frightening the family and causing them to destroy it as a group. Humans, like many mammals, are social animals and used to hunt and live together in packs. A group of humans could accomplish much more than an individual.