Yes, in the wild they will eat snakes, lizards, birds, etc. In captivity a little white chicken meat (no bones) is a good source of protein as is mealworms.
kiwis
fresh fruit like mango, apple, and bannana
fresh cooked vegetables likcauliflower, carrots, corn and turnip
sweet potatoes
nuts and seeds
hard boiled eggsinsects like meal worms, crickets, and...
Capuchin monkeys do not eat jaguars, they eat a different variety of food such as kiwis, fresh fruit, mangos, apples, bananas, fresh cooked veggies like cauliflower, carrots, nuts, leaves, and some...
Some monkeys do eat (or primates better said) chimpanzees are even caught on film ripping limbs from their own kind, and will lead to death. They'll eat the carcass and so that answers ur q.