Our savannah ancestors very likely consumed less meat than modern humans, like you said, but my point was that certain nutrients aren't too humans available at

Our savannah ancestors very likely consumed less meat than modern humans, like you said, but my point was that certain nutrients aren't too humans available at all without animal inputs. Agriculture (notice I didn't say modern agriculture) enabled lacto-vegetarianism by adding milk to get those nutrients, but that's 12,000 years out of...what? 50,000 years of homo sapiens sapiens existence? Those inputs aren't trivial, either, since a lack of B12 will cause irreversible central nervous system damage in adults after about 5 years and straight up kills children. Indian diets are also a great example here since the Kshatriya caste were the warriors and rulers and also included meat in their diet, partially for the caloric density to make transporting rations easier but also for the health benefits to get fighting fit. Most indians included at least some eggs and meat while none of them went without dairy, except in fairly narrow cases of ascetics for limited periods of time. The Brahmins, who had the strictest rules against meat, were not laborers, which should tell you something important about human physiology and heavy physical activity. Of course in the modern era, with abundant food, refrigeration, dietary supplements, and so on...sure, a legitimately vegan diet is absolutely possible. Historically? Not so much.