Luke Skywalker is quite the example of Campbell's Hero. First, the 'myth' of the Jedi and what Luke knows of his father are rather warped initially. Luke is called by Obi Wan to continue the legacy his father was supposed to carry out. Skywalker confronts the death of his aunt and uncle and must be "reborn" through the rigorous training of becoming a Jedi. Luke is the center of his own existence after Obi Wan dies and must pursue Yoda to further his development, training, and transformation into a knight.
Luke is called to adventure by Obi Wan, to save the galaxy from all that is dark and evil. Luke refuses the call at first, because he knows he must help his aunt and uncle with the farm. However, when they are murdered, this prompts Luke to avenge their deaths and join the adventure. The belly of the whale for Luke, in my opinion could be when he is on Hoth in Empire Strikes Back and the beast knocks him out, while Han Solo must cut open a Ton Ton and keep Luke alive.
Skywalker's trials are epitomized when he trains rigorously with Yoda. Our hero needs a goddess, unfortunately he is ignorant to the fact that it is his biological sister. Luke learns Vader is his father and refuses the call to the Dark Side. Luke is quite vulnerable when he learns his father is part of the Evil Empire and realizes everyone in his immediate family is either dead or on the opposing side in war. I'm certain Luke is feeling pretty low at this point in his journey.
Luke has nothing left "at home." The farm is attacked, he brings the droids with him, and realizes his purpose in life is far greater than being a farm hand on Tattooine. After Luke is nearly finished with his Jedi training with Yoda, he questions his reason for being alive. Leia and Han convince him that he is ready to take on the Evil Empire, with their assistance, but Luke will have the most weight on his shoulders.
Han Solo is Luke's Civic Hero. Solo began as a rambling, indebted "trucker" of the galaxy. Solo sees the transformation in Luke and is inspired to lead his community in a successful regime against evil, following behind the Jedi Knight that is Skywalker. The world's peaceful, just, and civil existence is far more important than Skywalker's feelings of himself. He questions the issues of the past, ie, the woman he loves is his sister, his father is evil and tried to kill him, his surrogates were murdered, he had to accept the hero's obligations, but ultimately resolves it all by partying with the Ewoks on Endor with his closest friends and is finally at peace when he sees Yoda, Anakin Skywalker, and Obi-Wan Kenobi in peaceful spirit form.