Sit down and hold on tight...
You are absolutely right about Tolkien's version of Aragon. Aragon is settled and has no conflict. But, even though Tolkien denies it, Aragon is a type of Christ, so I don't think there would be a conflict. He knows what he must do.
Jackson understood that Aragorn must be nuanced and gives him a conflict of fear (will he be Isildur's heir or rise above the weakness in his blood).
In fact, that is why I placed Samwise Gamgee as the hero of the book. Sam is an every man in extraordinary circumstances doing what is necessary to fulfill his role. That to me is a hero.
Or a hero is Pippin, who does what is right even though he is frightened.
Now, speaking of characters, the most interesting character in Lord of the Rings is Smeagol. I believe he was Tolkien's favorite and that is why he is drawn so richly.
Smeagol is heartbreaking...very, very good.