Jim's escape from freedom is not a well-laid out plan, just rather a lucky turn of events. Jim heard of being sold down river and ran away for the island in the river and if Huck didn't fake his death and preoccupy the town Jim probably would have been captured. When the two got on the raft and headed down river Huck protected Jim in a couple of close encounters like in the small pox incident. After meeting the Duke and King Jim had a easier time of hiding out, yet his search for freedom took a back seat to the Duke and King's greedy exploits. The King then turns around and sells Jim for $40 and Jim is locked away. Huck has a moral decision to make then whether or not to help Jim. I credit Huck with Jim's freedom even if it was planned out Huck still did it. Like when being on the raft with Jim, Huck was glad to have company I don't think he realized he was helping Jim. When the two slave hunters came up and questioned Huck, Huck was just saving his own skin and it just turned out to save Jim's as well. With the Duke and King Huck made sure they helped hide Jim and when Huck was not around Jim was sold. In the end Huck finally realized he needed to help Jim and this time he was going to do it knowing he was helping Jim as where before he didn't realize it. Even though Huck followed Tom in rescuing Jim in the end I would still credit Huck with Jim's freedom. The question would be whether Huck knew what he was doing when him and Jim first took off on the raft.
When Jim and Huck are on the river the two seem to enjoy some good times and seem to have some freedom. Their freedom is they do what they want and just lazy away the days. Huck is use to this because his old "unsiziled" ways is close to what they do on the river. Huck on the river does what he wants, when he wants, and does not have to explain himself to anyone just like it was on land before the widow tried to change him. Jim on the other hand probably never had such freedom doing what he wants and I think he really enjoys it even without his family.