Contrary to what others write*: Yes, the terminal.
It's not that you can't get by without it on many distros, for most things. But for even for medium and non-techy users, getting the fear of the terminal out of the way early will make their journey much, much smoother. It doesn't have to be much, no shell scripting or anything, just the basics, conceptually what a terminal is, what the shell is, how to execute stuff, maybe chmod +x
to execute, other utilities like ls
, cp
, mv
, mkdir
. maybe symlinks/ln
. That'll be enough to take away the fear if they see any "Now do this in the terminal" advice online (which they absolutely will, let's not delude ourselves), and maybe enough to get them to notice that "huh, sometimes the terminal is more convenient, they weren't bullshitting when they said that".
*) Since you asked about "beginner Linux users" and not users that "just want to use their computer and not think about the OS at all", I'm pretty confident about that assertion.
PS: I really think that's not too much too ask. I remember my mother learning DOS commands back in the day for a regular desk-job. Everyone can do this, it's not difficult, people just have to let go of a few false preconceptions drilled into them by the industry (MS, Google and Apple).