We already grind wheat to make flour and the process can be done by hand, we also have grown our own wheat and threshed and winnowed it in the wind, it’s very simple to do but is time consuming. Growing wheat might be a problem in the future but heat tolerance might be easier to evolve in it than humans.
I agree natural selection is brutal and the process is completely random but the outcome favors those best suited to the environment otherwise we would never have evolved.
I’m not sure humans are intelligent beyond the ability to communicate and store our knowledge, all we have accomplished has come about by lucky observations slowly building into what we have today, very similar to natural selection, it’s not dependent on a particularly high intelligence, someone observes something like fat melting and mixing with the ash in the fire and finding the ash will cut through fat and clean skins, or a fire on a beach creating a rough glass like substance, a diesel engine didn’t just get invented without thousands of years of accumulated knowledge.
I doubt a stupid animal would survive long, but agree we are as subject to same laws of natural selection as all other animals. I observe our cat, she might have a small brain in comparison to humans but she is not stupid and can learn far faster than my children ever could, if it’s of benefit to her, which is all natural selection has to do, be of benefit, then the chance of survival and to breed is improved.