You left out the simple, yet rather critical fact, that humans are the only animals who use fire to cook meats - making them more digestible and functional to eat with our teeth set. In addition, the use of tools allows us to eat foods that mountain lions have dentition for......... Our large brains evolved because we had access to proteins of high quality. And our larger evolved brains allow us to figure out how to eat almost anything. We are not carnivores or herbivores - we are the most opportunistic species ever evolved and more omnivorous.

Thanks to protein from meats, our abdominal cavity shrunk while our brains got larger. Our bellies cannot hold the amount of vegetation we would need to survive.

Pass the prime rib....