[AlotOfReading]

I'd recommend reading at least the the abstract of the paper linked therein, rather than the popsci summary. The authors are arguing that H. Erectus in particular was highly carnivorous (though not exclusively). That's about 1M years, not plural, and it's ignoring all the Australopithecines and H. habilis besides. The authors explicitly state that middle Pleistocene archaic humans moved back the other way and incorporated far more plants into their diet. By the time anatomically modern humans arrived, we had quite significant plant intake. Besides, the GP comment doesn't make sense archaeologically. We have shell middens from H. erectus and know that many archaic humans lived in near-coastal environments. There was no period in which we were purely pursuing ruminants even when archaic humans were more carnivorous.