@atomicpoet

Good way to not go crazy is to see protocols as how they send data first, then what can be build.

ActivityPub is most simple, works like a two-way RSS for servers to pull posts from each other.

XMPP is like TCP with navigation, with many extentions.

Matrix is a way to store and modify decentralized data in an abstract thing called "room" that it's members can access.

Of course this is only simplification.