You have it wrong. The official standard library is under constant development and in practice many people use it and not the Jane Street stuff.
the Jane Street side are quite prolific with blog posts etc
as a newcomer to OCaml one of the first, and nicer-looking, intro resources you'll likely encounter is the Real World OCaml book https://dev.realworldocaml.org/ which unfortunately does everything using Base instead of the stdlib
Personally that didn't sit right to me and I prefer to use the stdlib by default (which seems fine and not in need of a wholesale replacement)
Thanks in advance.