I think the answer to your question has several layers. I'll start with the most general layer and get more specific from there...
The ActivityPub protocol, which Lemmy and Mastodon (and other services) use to communicate, is published by W3C and was developed by a group of people. This page on W3C includes a list of authors. It looks like at least one author has a Mastodon account; I'm curious to see if mentioning them here will federate to Mastodon and get a response: @cwebber@octodon.social
Each Lemmy instance (there are >600 of them) was started by a different person. This is usually (but not always) the first admin listed in the sidebar on that instance's homepage. Sometimes the founder is not the most active admin; in many cases they have recruited others to help in order to spread the work and reduce the chance that the instance dies when the founder has some unforeseen life event. Here are a few people who started some of the larger instances: @dessalines@lemmy.ml (mentioned above) @ruud@lemmy.world @sunaurus@lemm.ee @TheDude@sh.itjust.works @db0@lemmy.dbzer0.com @smorks@lemmy.ca (took over that instance from a previous owner)
The fediverse has existed for much longer than lemmy has. I can put you in touch with the designers of the activitypub protocol, which the fediverse uses. I’m not sure what you need though
I just need a couple names or a single name so I can do an AMA Request and get it posted to AMA. I think it would be a neat interview and if need be i will send them the questions before.
Lemmy is a collaborative work, but my understanding is lemmy.ml was the first Lemmy but not the first fediverse tool. If someone more knowledgeable can comment please do.
The creator of Lemmy World is @ruud@lemmy.world. In my opinion, he's a super cool dude, but doesn't take crap from anyone. He's a master of boundaries.