Why are we considered omnivores when most of our anatomy suggests we are herbivores?

You've been misinformed. Our dentition developed as it is not because we are natural herbivores but because our ancestors began to cook their meat. Humans are the only animals that consciously do that. Meat is softer as a result so we don't need large teeth. We don't need to be fast or have claws for a similar reason. We evolved as tool users, we hunt with weapons. The bottom line is human brain morphology evolved due to a heavy meat diet and it's necessary to eat meat for our brains and bodies to develop fully.