This is the wrong question. Descent is a class of its own. No really.
It's a game that wants you to think in completely different ways from how you naturally do. That's never going to be immediately intuitive for a player who's starting it for the first time, no matter how you decide to introduce it to them. Neurologically, the brain needs time and practice to form those new connections and it's going to depend at least a little on the player's age and how much "exercise" they give their brain on a regular basis as well.
This is going to be as much an issue of neuroplasticity for new players as it is one of difficulty.
So you can try to ease the player into it but don't coddle them so much you give them the option of not learning, because they won't. The brain doesn't naturally rearrange itself when it doesn't have a reason to. If you want to include some harder puzzles, make like Portal and focus them around the game's central mechanics (in this case, that's zero-gravity movement) so the player comes away from each one with a better understanding of the game as a whole.