“Gay” used to just mean “happy” in English. Now it doesn’t. Language is fluid.
Gay still means happy in addition to now more common informal use for homosexual person.
Moron was originally defined as a psychology term for “a person of mild mental retardation” in certain IQ range. While the new informal meaning doesn’t relate to the technical term in psychology, it still means stupid person nevertheless.
Does society at large use either of those words in that context anymore? Not really.
Nevertheless, unlike “gay”, “moron” in the new context has almost identical meaning as the original definition.