It's an oversimplification, yes. You need to cover with a cloth or filter so gasses doesn't build up within and oxygen can enter. At the same time, you want to keep flies (which carry yeast and bacteria from rotten fruit, etc) away but also mold particles, pollen and dust. Temperature below 35C, or else other types of bacteria could thrive.
But really, you shouldn't use cooked food. Unless you provide a healthy strain of bacteria to it, like some mold cheeses are pasteurized, but then they add strains to it after.
I have just been so surprised to see videos of people eating rotten meat and not getting sick. That is, them having a low enough stomach acid (1,5 pH) and the meat being fermented sourly. Would not have worked with rotten cooked meat. Then nekros bacteria would have taken over, made it alkaline and toxic.
