I looked a bit into the etymology. It is not helpful. Cook as a noun or to cook means the same thing all the way down to Latin coquus and to PIE *pekʷ-, with only the later having one more meaning: to ripen. Heat application is there all the way, but not really specifying how. I would suggest that probably people boiled or simmered more than they roasted in historical times, because, well, convection, that makes even hardest meat sooner or later soft without burning it, and does not waste nutrients into the grease falling into the fire. For example, if you have an old rooster, a soup or a stew is really the only option.

However, roasting seems to be a higher-prestige way - medieval nobility is commonly depicted feasting on whole roasted animals, not sure how accurate that is. Perhaps the prestige comes from the difficulty. Roasting a whole ox, which was a way inviting a whole town to party, is very, very difficult.

Back to practice: I recommend telling people "learn to prepare a few easy meals" this sounds less scary than "learn to cook".