Hi Den! The rating system is indpendent of other ratings. I listed the 6 different rating categories on the main page, which will appear when the submission period ends. Check out the results of this game jam to see. . . it has multiple categories and no overall winner): https://itch.io/jam/3rd-hawktober-game-jam/results
It's okay to tell people if you have a submission! Early ratings will not affect the jam ratings. Just make sure they try to rate some games when the jam submission period actually ends.