This is a worthwhile read, both for the Fediverse n00b and us grayhaired GenX digizens.
https://www.theverge.com/2023/4/20/23689570/activitypub-protocol-standard-social-network
I don't agree with every statement, but it's got a good backgrounder (despite completely missing Usenet) and some well-grounded "where to next" predictions.