The Forest Video Game, how do the cannibals survive?

This question has 2 parts

Part 1: The only food source they feed on is human flesh. The problem with this is that the only people we can find them feeding on are the ones who were on the plane when it crashed. So what humans have they been eating prior to the crash? If we look around the penninsula you’ll see bodies and body parts that would equate to hundreds or thousands of human lives. A plane can hold up to 800 passengers, so it could be accurate but I feel there are more than 800 lives taken from all the body parts and bodies. Even if the count is accurate it still does not explain who they were eating prior.

Part 2: How could cannibals form any kind of society at all, wouldn’t they be killing and eating each other? I doubt they are civilized enough to have a pact to not eat each other.