According to archeologists our prehistoric ancestors started off on a plant based diet. They would not have been able to tear flesh or hide with their hands or teeth. With the discovery of fire and the use of tools our ancestors ate modest amounts of meat during periods when plant foods were unavailable.  Humans, unlike animals, have to cook meat in order to avoid being poisoned by pathogens such as E.Coli.
Meat and dairy are not the most appropriate types of food for humans. A lot of research shows that meat and dairy can contribute to cancer, heart disease, diabetes and obesity.