Humans were never hypercarnivores. Neanderthal consumption of maggots clouds the data.

Excerpts from an interesting paper in Science Advances.

Reconstructions of Eurasian Neanderthal diets based on stable nitrogen isotope ratios (δ15N) typically place hominins at the top of the food web, together with, or above, hypercarnivores, such as lions and wolves. We suggest that these high δ15N values may, in part, reflect the regular consumption of 15N-enriched fly larvae (maggots) occurring in stored animal foods. The ethnohistoric record contains countless examples of Indigenous peoples routinely consuming putrefied animal foods with maggots... We suggest that frequent consumption of animal foods laced with maggots should be considered as a contributor to the high δ15N values observed in Late Pleistocene hominins...

Indigenous peoples almost universally viewed thoroughly putrefied, maggot-infested animal foods as highly desirable fare, not starvation rations. Many such peoples routinely, often intentionally, allowed animal foods to decompose to the point where they were crawling with maggots, in some cases even beginning to liquify, and inevitably emitting a stench so overpowering that early European explorers, fur trappers, and missionaries were sickened by it. Yet such foods were viewed as “good to eat,” even a delicacy, and when asked how they could tolerate the nauseating stench, they simply responded, “we don’t eat the smell”. While our Western sensibilities might abhor the thought of maggot-infested foods, one even finds vestiges of larvae consumption in Europe with the delicacy of casu marzu, a traditional Sardinian cheese replete with the larvae of cheese flies (Piophila casei)...

Our principal goal in this study was to determine whether 15N enrichment occurred in maggots raised on putrid tissue and whether the degree of enrichment was of sufficient magnitude to account for, or at least contribute notably to, the unusually elevated δ15N values observed in Eurasian Late Pleistocene hominins...

Many nitrogen isotope studies place Late Pleistocene hominins alongside hypercarnivores, giving the misleading impression that both had broadly similar diets. They did not. Hominins are primates with largely vegetarian-derived digestive and metabolic systems, not specialized flesh eaters. While it is possible for humans to subsist on a very “carnivorous” diet, many traditional northern hunter-gatherers such as the Inuit subsisted mostly on animal foods, hominins simply cannot tolerate the high levels of protein consumption that large predators can. A modern human weighing ~80 kg, the estimated body weight for a robust cold-adapted Neanderthal male, cannot consume more than ~300 g of protein per day (<4 g/kg of body weight) without serious health consequences. At sustained intakes above that level for as little as 1 to 2 weeks, the individual becomes vulnerable to a debilitating and potentially lethal condition known to early explorers as “rabbit starvation”...

In modern medical terms, the consumption of such high levels of protein exceeds the capacity of the liver to up-regulate enzymes involved in the synthesis of urea, with the result that the liver can no longer effectively deaminize the amino acids, leading, in turn, to a buildup of ammonia and excess amino acids (hyperaminoacidemia) in the blood. In notable contrast, a modern African lion can readily subsist on protein intakes that would probably prove lethal to a human in a matter of a few weeks. Thus, northern hunter-gatherers were carnivorous only in the sense that they relied heavily on animal foods, but most of what they ate was fat, not muscle...

To stay below the critical protein threshold, hunters deliberately targeted the fattest prey available at a given time of year and harvested mostly the “choice parts” of their kills, i.e., the brain, tongue, briskets, ribs, adipose tissue, fatty organs and entrails, marrow, often the carbohydrate-rich chyme and partly digested stomach contents, and, time and fuel permitting, also the grease in the cancellous tissue of the bones...

...meat and fish surpluses were procured in the summer and fall; processed by drying, salting, or freezing; and cached for later use…. The preparation of food surpluses was an intrinsic part of the seasonal round.” Such reserves were often repeatedly tapped over periods of weeks or months, many over multiple seasons, and some for a full year or more. Foods were often already maggot infested before they were placed in caches (i.e., in summer and autumn), and, by the time that the contents were lastly exhausted (commonly in winter and/or spring), they were almost invariably in an advanced state of putrefaction and filled with both living and dead maggots...

I think this is absolutely fascinating, so I've excerpted way too much, but I encourage interested readers to go to the primary source for more data and discussion.  The general public will focus way too much on the "ick" factor of eating maggots, but there are serious matters to consider here re components of a healthy diet, limitations of protein intake, and the consumption of fat.  In particular, this report gives me new insight into the well-known use of "buffalo jumps" to slaughter entire herds of large animals, such as at the Itasca (Minnesota) Bison Kill site and the more famous Head-Smashed-In Buffalo Jump in Canada.  I had always viewed such hunting techniques as extravagantly wasteful, but now I understand that humans could return to the kill site months later to harvest meat, fat, and maggot.

You learn something every day.