How about this? people who won X consecutive times, can't be selected as winners, but they'll have their rank.
Basically, "You were ranked first in this jam, but since you've won the previous one or X consecutive times, we could not award to you this time".
So people who are here with the sole desire to boost their ego / beat up beginners, won't be here for long I guess... I just think that there's not many people like that. It's too much effort for little return... Also imagine their itch page, won 30 beginners jams or something like that ... it probably doesn't look very good, does it?
And though Learning should be the focus for beginners, a little competition helps. Seeing how your peers are doing can give you a glimpse of what's possible if you continue to work hard, it lets you know too how far behind you are.
So my thought are, if you're beginner, don't bother too much with who wins. As you learn more and become more experienced, you'll eventually join a "harder" jam yourself, in order to surround yourself with more skilled people and continue to improve...
after all, it's not fun being the super smart top student at first grade for 10 years..
Cheers ;)