I have doubts
The ones that always come up, answered without jargon.
“It's too complicated.”
It's like choosing where to have your email. You pick a server, make an account, and you can talk to people on any other. If you don't know which, join a big one: it isn't a decision for life.
“There's nobody there.”
There are millions of accounts, and Mastodon's main server alone has around 270,000 people active each month. What happens is that your screen starts empty, because nobody picks what you see for you: follow ten accounts on topics you like and it changes completely.
“If my server shuts down, I lose everything.”
You can move to another server and take your followers with you. What you've posted doesn't travel, but you can download a copy whenever you want. And it's a good idea to start on a server with a few years behind it.
For the curious
When you move, your old account points to the new one and each follower's server switches them to follow you there, with nothing for them to do. Posts stay behind, because they live on the server they were written on.
“It's only for tech people.”
It started that way, but today there are artists, bookshops, journalists, neighbourhood groups and people sharing photos of their dog. The directory has corners for all of that in Spanish and Catalan.
“Without an algorithm, I'll get bored.”
You see what the people you follow post, in order, and nothing else. To discover, you follow hashtags (#film, #hiking) and look at what gets shared. It takes a little more at first; after that, your screen is yours.
“What about Bluesky? Isn't it the same?”
It looks similar from outside, but no: it uses another system and, for now, nearly everything goes through one company. The fediverse is thousands of servers with no common owner. Even so, they can be connected.
For the curious
Bluesky uses the AT Protocol and the fediverse uses ActivityPub. Bridges such as Bridgy Fed translate between the two: if an account opts in, it can be followed from the other side.