It was coined in 1976 as a term meaning "information virus" (akin to gene) something that manages to get itself copied by using its hosts, humans. It still sort of has shades of that meaning in its modern usage, but the original usage was more serious... useful for discussing things like how religions evolve self defense mechanisms.

Nice to see Wikipedia still talks about the old meaning, and uses "internet meme" for the newer meaning.

https://en.wikipedia.org/wiki/Meme