You may be interested in this thing I wrote:
https://qcb.neocities.org/mastodon
It basically gives the rundown on said lore, highlights what BIPOC (esp. Black) people should expect, and how to get started on Mastodon with all of that in mind.
I'd love to see more BIPOC (esp. Black) people in the Fediverse, but fully informed, you know? (So... like every other social media ever, basically.)