stupid person vs simple

stupid person and simple both are nouns.

Word	Noun	Adjective	Verb	Adverb
stupid person	Yes	No	No	No
simple	Yes	Yes	No	No

As nouns, simple is a hypernym of stupid person; that is, simple is a word with a broader meaning than stupid person:

Other hypernyms of stupid person include simpleton.

stupid person (noun)	simple (noun)
a person who is not very bright	a person lacking intelligence or common sense
	any herbaceous plant having medicinal properties

stupid person (adjective)	simple (adjective)
	(botany) of leaf shapes; of leaves having no divisions or subdivisions
	having few parts; not complex or complicated or involved
	easy and not involved or complicated
	exhibiting childlike simplicity and credulity
	unornamented
	lacking mental capacity and subtlety
	apart from anything else; without additions or modifications