Michael Pollen wrote The Omnivore's Dilemma. A good book exploring four meals - the industrial meal, the industrial organic, the natural farm organic and the harvested from wild.
He describes what goes into each meal, the nature of the farming or manufacturing, the delivery to the end consumer and the tastes.
It mentions in the book the concept that Omnivores developed larger brains than either carnivores or herbivores because there were more options to keep track of, and food combinations and places to find food, and dangerous non-food items to avoid. It simply required more brain power to manage surviving as an omnivore because of the choices. "What shall we have for dinner?" is a basic thought that plagues the omnivore who has a ton of options.
There are a lot of omnivores beyond Humans, so that doesn't make us human. But I think we come from a branch of homonids that was really more adventurous and hell-bent on being super-omnivores. They got on a quest to try just about anything and experiment ruthlessly in the environment to find anything and everything that could possibly be eaten.
And we've never stopped.
I'll call it the "Insatiable Foodie" theory - it really explains most of our society. Some day they will boil down the difference between humans and apes to the Insatiable Foodie Mutation gene. No other creature on earth will have it.
When we some day meet Aliens space travelers, they too will be in the search for the ultimate variety of food - if they weren't they wouldn't be smart enough to be space travelers! - so they will probably eat us.