Meme was coined by Richard Dawkins in the Selfish Gene (1976), where he meant to make an analogy between how...

....well, genes basically operate as a self replicating instruction set via things like plants and animals... or virii / viruses.

In that sense, we live in a gene-world, where genes perpetuate themselves, spread and grow and are the primary drivers of dramatic change and growth and collapses.

But ideas, notions, attitudes, philosophies... these become powerful enough once they are embodied by biology capable of contemplating them and acting on them, at scale, that they can actually override genes as the fundamental driver of change in the eco/biospehere, and they also propogate and essentially vie for dominance or prevalence amongst each other in similar ways as genes do.

So... 'meme', because it sounds close to 'gene', and also because of similar sounding roots in greek, 'mimesis' essentially meaning 'behavioral imitation'.

https://www.etymonline.com/word/meme

'Meme' itself was not widely used outside of basically academia untill it gained a more specific meaning in the roughly the late 90s / early 2000s, as referring to a kind of (usually goofy) image or video that spread virally across the online world.

To my knowledge, you did not broadly have people emailing each other goofy ascii art in the 80s and referring to that as a meme, nor widely or within a niche subculture referring to any kind of idea or cultural craze of the time... certainly at no where near the scale and popularity of the term nowadays.

If you wanted a meme from roughly the time that the term 'meme' was being broadly popularized to mean 'online internet joke image', you'd be looking at basically demotivational posters.

I meant more like three start of easily shared online memes.