The character of Creon has been the subject of debate from antiquity to the present. He is an interesting and complex character. In many ways, he is a patriot, striving to do what is best for Thebes and end the fratricidal wars and civic unrest that were tearing the city apart. He is intelligent and rational, trying to avoid being swayed by emotion and attempting to think rationally about how to solve the problems of the city. He is less pious and superstitious than many of his compatriots, reflecting the "modern" Athenians of the Sophistic Enlightenment.
Sophocles, though, himself a deeply pious man, sees Creon's rationality as problematic and arrogant. Creon's refusal to favor his own family is in some ways admirable, standing up against favoritism and corruption. However, this very fair and rational character means that he lacks empathy. He is also arrogant and authoritarian, trusting in his own intelligence. As the play shows, however, his intelligence and fundamental moral uprightness lead him to reform, although unfortunately, this occurs too late to avert a tragic ending.
The very anonymity of the Guard suggests that he is intended as a character type rather than individual, representing a typical citizen rather than a great hero. He is basically a man trying to do his job but lacking any great insight or imagination. He represents the sort of average citizen of Thebes that Creon should be leading and protecting: decent, honest, but not overly courageous. Creon's paranoid reaction to the Guard reveals the central flaw in Creon's character and his failure of leadership.