That was a lot of years ago and AFAIK she has not really danced since and the dancing they did in that movie didn’t cover the gambit of the dances in DWTS. It definitely would disqualify someone like Patrick Swayze (were he still alive) as he was a professionally trained dancer — like all the professionals on the show.
I read a bio of her recently. She attended the Dalton school where she studied acting and dance. She also danced in a Dr. Pepper commercial at the age of 19. So she had enough dancing skills to get that gig. Hardly a novice.
However I do think that Nicole from the last season had more dancing experience than Jennifer had. There was no contest there.
The professional ice skaters all take ballet and dance. It hasn’t been a level playing field in many of the seasons recently.