Each species eats those very foods that are easily accessible in the natural environment of the given species. Before our ancestors left their original habitat, the tropics, they had been living on the foods they would find in their environment.
Sweet fruits were a preferred major source of calories. (1)
However, it has been observed that the anthropoid primates (primates that resemble humans: walk on two legs and have no tail) hunt when they do not have their preferred food, that is, they hunt for survival as well as when they are defending their territory.
It is probably safest to say that our ancestors were gatherers who hunted in order to survive when the food source was scarce.
People around the world today eat what is available to them. Most people today do not choose the optimal diet because of their dietary beliefs, or because of financial reasons. Plus the science of nutrition is still in its infancy, and misinformation about nutrition has long been prevalent, all of which affect people’s food choices.
The good news is that we are now able to adapt the sub-optimal parts of the Planet we have inhabited to our optimal needs. This is now possible for the first time in human history. We have come a long way in the fields of science and technology, so it is a high time to apply the acquired knowledge and experience to the expansion of orchards and edible forests, and thus health.