I think while it makes sense to focus on this in trying to capture the qualitative aspects, it doesn’t quite describe the content as a whole. I don’t think any particular instance not possessing a usual property disqualifies it from being classified as the same.
Many people could look at a terrible attempt at a meme but still recognise it as a meme by it being some sort of template for example. So I don’t think popularity or humour is necessarily a requirement, it’s just that the typical meme examples that come to mind are popular or funny etc.