The theme of this movie is introduced by the captain of the shrimp boat in Clark's opening scene. After he saves Clark from being "squashed" by a falling cage this captain bestows on him a defining label with one question: "Where the Hell'd they find you, greenhorn?" and it is from that moment that greenhorn became Clark Kent's middle name.
Clark's inexperience with who he is and what he should be is the beginning and end of the M.O.S movie. Throughout the film, greenhorn will describe how Clark not only dealt with the complications of being an alien with special powers but also how he managed his growing anger at being abandoned by his real parents and bullied by the weak humans of his adopted home.
On the burning oil rig, an unkempt and unshaven Clark saves lives, openly flaunting his strength and invulnerability, without thought of future consequences, nor concern for the reaction of those who witnessed what he could do. While being helpful, Clark was almost martyr like in how he approached the fire, abandoning all propriety and secrecy. This was most likely due to the fact that he was not fully aware of his ability to blow out such a fire or it was a touch of rebellion to his father's exhortation to keep that part of his life a secret.
Later, we see Clark, as a kid, overwhelmed by his enhanced senses. Unable to control his x-ray vision and hearing, he runs from class, shutting himself in a closet until his mother's wise, loving voice calms him enough to focus and reign senses. While waiting for his mother to arrive. Clark heats the door knob rather than holding the door closed against his teacher or any of the laughing students barging in. Perhaps this was a passive way of punishing his classmates for their ridicule of him.
In the next scene, we see Clark stealing clothes, a sign he has yet fully developed the extents of his moral compass.
In what is probably the first time he has truly expressed his anger towards a bully, during the non-fight at the diner where he was employed, Clark impales his antagonist's semi-truck with several logs. This not only punished the bully by taking away his livelihood, but it also foreshadowed how fed-up the passive alien had become with piss-ant tyrants.
This latter revelation is important because it showed how years of being taunted and bullied as a child and as a young adult, while maintaining passivity, had created a darkness within Clark that festered into a powder keg of penned up anger with no way for the pressure to be released - that is- until Zod landed on Earth, revealed his intentions to kill everybody while Terra-forming the planet into a new Krypton and made the huge mistake of bullying Clark's mother.
It was then that the Powder-keg exploded.