Jim is the ne'er do well kid to Marlow's well meaning if a bit frustrated father-figure. Jim makes mistake after youthful mistake, and Marlow picks up the pieces when he can. In many ways, we might think of Lord Jim as the story of a young man struggling to overcome an impulsive mistake. Jim hasn't had a ton of life experience, after all, and he might be ill-equipped to handle the challenges life throws his way. But can we write off all Jim's troubles and bad decision making as a product of his immaturity? Or is there something more deeply wrong with his character?
Jim's youthful inexperience leads to his his rash actions aboard the Patna. It has nothing to do with his inner character.
Patusan equals Neverland. Once there, Jim becomes a perpetual youth; he never grows up.