I think it's important distinguish between being an herbivore, and being a vegetarian.
Humans are omnivores regardless of what they choose to eat--the Inuit aren't carnivorous people simply because they eat animals almost exclusively. They are simply eating what is locally available. The ability to eat things on either extreme is a part of what makes humans adaptable. It's just easier for humans to eat only meat than it is for them to eat only vegetables. That's why the Inuit stay healthy, but you find 0 vegetarian primitive cultures. Vegetarianism is only associated with more advanced cultures...and usually with religion, up until VERY recently, making it a cultural construct.
It is fascinating that some humans actually choose to avoid certain readily available and accepted foods, however. You don't see THAT sort of behavior too often in other species.