Yes, git can be complex. It's also a requirement for modern software development. It is well documented, and not esoteric.
If someone hasn't taken the time to learn the tools their team uses, they will be a burden to the rest of the team. They don't need to become an expert, just experienced enough so they don't cause problems for others on the team.
I've never seen documentation on Git that was good and accurate. Pretty much every explainer out there commits major errors, claiming things like: commits are changesets, branches are sets of commits, claiming that any Git operation can be undone, implying merge is a symmetrical operation, or saying to never force push.
My company handles this by allowing them to study on the dime. I just ask how much time they want and ask them to do it, and if they need some material or help devising a study plan.
Curiously the two that needed it didn't really want to study at all, and we eventually let them go (they were interns).
If someone hasn't taken the time to learn the tools their team uses, they will be a burden to the rest of the team. They don't need to become an expert, just experienced enough so they don't cause problems for others on the team.