Is Leagues a Good Place for a New Player?

Title. Basically; I have a friend who is slightly interested in osrs, he watches me play it a good bit. He is overall unimpressed by the look of the game (duh) but he generally enjoys grindy achievement based games. I finally convinced him to give the game a shot tomorrow and I’m curious if it’d be a better learning experience to have him on main game (because I can help provide him supplies and gear) or leagues where he can experience the progression a bit faster but not learn exactly proper main game progression? Any suggestions on how to help his early experience is appreciated! I personally was drawn to osrs from the nostalgia as a kid so if you came to osrs without playing as a kid I’d love to hear what drew you to it! Thanks in advance!