I think that your clarifying explanations of three English words, in terms their linguistic relativity, make good sense.
However, I’d like to bring up some of other possible angles within the legit interpretations of these three words as food for your thought.
Under some circumstances, the word “stupid” may not contain any derogatory connotation at all. For instance, in the acronym, KISS, - Keep it simple, stupid! “Stupid” actually means the opposite of being stupid, it actually gives implication to be smart or prudent instead.
As per your interpretation of Job’s famous phrase “ Stay foolish”, I personally believe that what he might mean is that people should think out of box which often confines us with our social and engineering norms. Further, unlike what you’d conceive as to play “dumb” or stay in low-key for the word foolish, Jobs might hint us to be courageous in challenging the establishments and conventional wisdom, to which, any deviation from normal conventions and traditions would be considered as unorthodox and foolish. Allow me to give you an example to illustrate my point, Galileo Galilei (1564-1642) an accomplished astronomer and physicist was trying to persuade the Roman Catholic Church to accept heliocentric theory. Obvious, he was label by people some of them were powerful then as a foolish fool. Well, since you’ve already know the end of the story, so I’d leave it here. :)
In short, the meaning(s) of a English word may not be always as tantamount as we would perceive per its face values. In fact, an English word may often changes or redefines its original definitions to convey the new apprehensions when time, context, speaker, tone, subculture and other factors come to play.
As you may know already, English is an interesting revolving language though it long history. So, learning and using it as an effective tool to express ourselves precisely and persuasively is definite challenging time to time, but it can be fun as well.
Thanks you for share your understanding with us, appreciated!
