Look, this is speculative, but we all need new lenses to see the world through.
Some have said that putting fire to use, not just for a light or weaponry, is what made us anatomically human. The timeline generally checks out (cooking and anatomically modern humans at least basically line up), and the massive change to our diet would very plausibly impact our digestion and energy systems.
But, of course, the above book is a bit strange. The weird thing about us isn't our diet. It's that we're so freaking smart! We all learn languages, with fully recursive grammars and tens of thousands of words, and languages don't do anything! They just help us learn other things!
Social learning seems much, much closer to the mark, when it comes to "what made humans unique". But you can't just magically process and partially digest food outside the body. Someone has to tell you how to do it successfully. Which things are good to eat, and how do you prepare them? Where are they now? Where were they before? If you feel sick, why is that? How can nourishment help you feel better? We know nixtamalization is quite ludicrously complicated and easy to screw up, and that's hardly unique.
I think it's worth squaring the circle on this and guessing that language, high-trust information transmission, cultural knowledge, and our use of novel tools are all parts of a whole: the human brain is here to help us cook.