Great explanation! Really well written and clearly explained. However...
Forgive my bluntness, but people not into tech tend to be lazy and stupid about everything lol. I feel like they'd take one glance at that, think TOO MUCH TEXT, not read it properly and still complain about the Fediverse being confusing.
Any kind of attempt at explaining the Fediverse seems to really confuse people, so IMO the best solution is to not even bring it up. Kinda dismiss it as no biggie, then sneak in a quick explanation at the end. Here's my go:
"If the word 'Fediverse' confuses or scares you, ignore it. Just join any Lemmy instance you like the look of. They all work more or less like Reddit. If you can't find a community/subreddit you want on one, make it yourself.
Or, alternatively, use this to see if one exists already. If it does, you can copy the community Lemmy address (it appears on the right in blue under the 'create a post' button in a form like '!linux'), search for it on your site's search, then subscribe like you would any other subreddit.
That cross-site subscribing is what the Fediverse is about - it's a bunch of small, independent Reddit-ish clones cross-talking. But since they're small, they're struggling and slightly breaking with Reddit refugees at the moment. I'd recommend local communities only for now. Join the commuities you find via Feddit in maybe a few weeks or so once everything's calmed down."
firebat