We’ve come a long way since then. Humans separated from our closest primate relatives, the chimpanzees, 7 million years ago.
We’ve been specialized in meat/fat eating for a very long time. More than 2 million and probably at least 3 million years.
I don’t deny that we can eat plants and carbs. I don’t deny that we use glucose for fuel, nor do I deny that some cells must use glucose. We also have a metabolic process to synthesize any and all required glucose. I’m saying our ancestors did not get much if any nutrition from plant sources because until the advent of the agricultural revolution the available plants were mostly indigestible cellulose. So they were not a particularly worthwhile ‘food source’.
Yes, our paleolithic ancestors would have eaten every food source available to them. Plants were a very small insignificant part until the agricultural revolution.