(2/?)
For a start, we also need to thank Evan Prodromou and the StatusNet crew for creating OStatus. Also Matt Lee and Mikael Nordfeldth for forking StatusNet to create GNU social, which the original Mastodon was designed to be compatible with.
Not to mention Christine Lemmer-Webber, Jessica Tallon, Erin Shepherd, and Amy Guy. Along with Evan, they led the W3C group that wrote the ActivityPub spec. Which allowed the fediverse - including Mastodon - to become what it is today.
(3/?)
That's just the tip of the iceberg. It would be remiss of me not to mention Mike MacGirvin, creator of Friendica, Hubzilla, Zap, Forte, etc. Pushing the boundaries of what decentralised social media can do, both outside the fediverse and within, since the early days.
Also the Diaspora team, who pioneered non-public posting. Also Lain and the Pleroma team, whose experiments like LitePub and Object Capabilities have also driven innovation in the space.