In the book, Parzival starts out low level because he lacks the cash to be able to afford to travel to planets where he can actually play the game. (Travel to his school planet is free.) He mentions getting lifts from people occasionally to kill low level rats and such, but he hasn't done that much.
In the book, this is a bit of a problem, because the first dungeon is a D&D dungeon...but apparently his knowledge of the layout of the dungeon allows him to get through it safely. After passing the first gate, he wins a prize consisting of lots of in-game money, which he uses to grind to being top level...but I don't think that being leveled helps him much, if at all.