Cooking roughly doubles the nutritional value of food. The heat breaks down complex, undigestable molecules to simpler ones. It also eliminates bacteria and parasites.
Most species would benefit a lot from cooking food, if they could figure out how.
Somewhat controversial book on how fire shaped our species: https://smile.amazon.com/Catching-Fire-Cooking-Made-Human/dp...
On the contrary, cooking destroys enzymes and evaporates water-soluble vitamins.
Bacteria are also very useful for digestion and all meat is aged even today (obviously).
My take is that it was simply a chance discovery of enhanced taste.
Fermentation & aging by bacteria on the other hand does breakdown meat and eases digestion, and it's a tradition all cultures have kept in some form, as evidenced by numerous dishes still consumed today.
Countless evidence proves that meat always constituted a small fraction of human diet from the paleolithic.
Starch has always been the main staple food.
I just doesn't make sense to me, humans always were the most effective hunters and meat is much more nutritious than starch.
But our past as successful hunters definitely has evidence, my favorite is our domestication of wolves.
Here is a study showing that cooked meat provides significantly more energy than raw meat.
I still am not convinced from my own experience, replying to another user I mentioned that when eating raw meat there is noticeably less residue, which would indicate more is assimilated.