These proto-memes were probably independently "invented" on a lot of different forums. There was a much bigger emphasis on making content yourself back before content aggregators, which meant there was a lot of innovation going on in a lot of places. They'd sort of trickle through the internet through some sort of weird back-channel osmosis and merge and intermingle to create new formats.

I think almost anyone who spent a decent amount of time in forums aimed toward adolescents around 2000 will have had some small impact on the emerging meme format.