  While both Huck and Jim can be seen as heroes, Jim is the more siginificant hero of the two because of not only the racism he faces by being a slave, but because he can overcome this racism by saving Tom in the end of the book. In Tom's cruel and "adventurous" plan to help Jim escape to freedom puts Jim in a place where he is locked in a cabin, when he could be free. Jim doesn't object to this plan because he figures that Tom is white and thus knows what he is doing.
After putting Jim through a month of being locked up, Tom does manage to help Jim escape. (even though Tom is shot in the leg) This is the point that seperates Jim's heroism from Huck's.....Jim throws away the freedom that he has endured a month's "cabin fever" for to save Tom that has just put him through this month of isolation. 
