The evolutionary step of eating meat, rather than vegetation, was what provided our ancestors with the evolutionary advantage over our competitors. Meat has a higher caloric content than vegetation and provided them with the energy needed for advanced brain development.
Interestingly, the second evolutionary step of cooking meat rather than eating it raw (which came around 250,000 years ago) fulfilled the same purpose as the first evolutionary step of eating meat in the first place: cooking meat makes it easier to eat and increases its caloric content. So, if we hadn’t learned to cook and eat meat, we wouldn’t be here today.
The ONLY REASON that people can survive today on a purely vegetarian or vegan diet is because of the abundance of food that is available to us (mainly due to the evolutionary step from hunter-gatherers to farming and agriculture around 10,000 years ago).
So, if you want to talk about what is “natural”, if anything, eating meat (and indeed cooking it) is more “natural” than living on a purely vegetarian diet; arguably, a feat only made possible by our modern lifestyle.