A shitpost doesn't have to be low effort, rather I'd argue the greatest ones are often quite high effort, and invoke a sense of poetry and lucidity that makes you question what could've gone on inside the head of the person that made it. That style of shitposting was part of the culture of 4chan's now-defunct textboards, and even back then it was markedly different from (and for the most part ignored by) the rest of the site.
For what it's worth, copypastas are the highest (and likely the oldest) form of meme.
For what it's worth, copypastas are the highest (and likely the oldest) form of meme.