Emacs' built in help is pretty good, I think. If you teach someone C-h f for function help, C-h k for keybind help, etc. I think they can get pretty far. The which-key package is great for discoverability as well. You can start pressings keys and then see a map of which next key presses do which action. I used vim for years, but always used a search engine to figure stuff out. I think Emacs got it right here. There's also the graphical menu system in Emacs, but I've always hidden it and avoided it.