Technically, yes, those are all ableist terms due to the way they enforce a hierarchy of cognitive ability. Calling somebody “stupid,” “dumb,” “idiotic,” “moronic,” “insane,” or the r-slur in a pejorative manner is basically telling them that nothing they say is of value to you because you think their brain is less capable than your own of forming a coherent point. Some of these are just considered stronger than others for one reason or another.