Let's say you want to introduce someone to RPGs...
For new players, don't bring them into a full system at all.
Savage worlds is probably the best, because of the fewest mechanics to bother with initially, yet more complex mechanics can be explored.
Whatever system you use, create their character for them by asking them about their character ask narratively, not mechanically (I.E. don't ask what class they are, instead ask what there character does for a living, or how they fight enemies, then pick ghe class that best fits their answer.)
Then, do not show them an entire sheet. Just a few descriptives (name, height, weight, hair, etc), the ability scores, and skill list. Play a session with just that. Don't worry about all the other modifiers or special abilities, not even for enemies.
Then the next session, each encounter pick one mechanic to teach them, and make the encounter all about that mechanic.
Repeat till they have been introduced to all the major mechanics (feats, perks, sliding/shifting, Attacks of Opportunity, etc), then have a boss battle bringing it all together.
After that, play normally, paying special attention to the small/rare details such as environmental effects.