Chickens really do remind me of people - and not just people, but specially human bullies.
The thing is, there basically aren’t any really herbivorous mammals, whatever people say. Sheep, cattle, deer, rabbits, etc. have all been observed killing and eating other vertebrates.
Chickens are recognized as omnivores, though most people don’t realize how effective they are as hunters. I used to have a compost bin next to the chicken house, and mice would nest in it. When the compost got disturbed, the mice would come running out - any that made the mistake of running into the chicken pen were goners. The chickens would casually snatch them off the ground, break their necks and tear them apart. They almost make cats look like amateur predators in comparison.