Let me make something clear, what an animal eats isn't what determines it's biology. An omnivore is an animal which depends on nutrient from meat and plants, as in if they don't eat both they live a shorter life. Carnivores can eat just meat and live its longest life, and herbivores can eat just plants and live a long life. They don't need to eat meat, but can and have been known to eat meat when starving or hungry, some herbivores can absorb some energy from meat but long term meat is negative for herbivores and causes problems, as they need plant based food. This is usually why animals hibernate in the winter.
I can eat stones, it doesn't make me a stonivore. What an animal is, depends on if their body can absorb or deal with what it eats. Squirrels mostly eat herbivorous, they are herbivores based on their biology, they can absorb meat but not well. A lot like humans can absorb meat but not well, most humans are actually herbivores and occasionally some have a mutation which means they need meat and are omnivores. So to be clear if you can live a long life without eating meat you're a herbivore. If you have to eat both meat and plants than you're a omnivore, if you have to eat meat to have a long life you're a carnivore. It is actually rare that animals need both meat and plants to live a long life. Usually wild animals go one way or the other, par in extreme circumstances.
A lot of books say humans are omnivores but it's just not true as humans don't need to eat meat to live and tend to live longer when they don't eat meat. Meaning most humans are actually herbivore. Some humans have a mutation and need to get a certain protein from meat, but this is 1 in 20 people. These people can supplement if they wish, or in the future eat lab grown meat if they wish to be vegan. But that is their personal choice.
Humans do a lot which isn't natural in the terms of biology, take drugs, drink and live in higher levels of radiation. Point being humans are always pushing their limits. Some would say building tools is unnatural but I think that is natural, we use our brain to work out ways to adapt. I don't see that as any different from an animal using claws. It's just humans have become so good at thinking that they can now do things way beyond their biological limitations. Like fly a plane or use a laptop. However our bodies have not adapted well to eating meat.