In looking into this question, one must consider the entirety of the story of Oedipus. Fate led Oedipus into fullfilling the prophesy of the Oracle of Delphi. He does not knowingly kill his father and marry his mother. His quest for the tuth leads him to the discovery of his identity.
Creon tries to make the best of a bad situation but by taking sides in the feud between the two sons of Oedipus and Jocasta, he brought down the wrath of the gods. To leave a body unburied was an offense to the gods and Etocles had violated the terms of the agreement to rule Thebes.
Antigone felt it was more important to follow god's law rather than man's law aka Creon's law. Her reasoning was simple, it was better to break man's law than god's law because gods were much more powerful than kings.
It can be argued that Creon is the tragic hero because he displays hubris in defying the law of the gods, but the true tragic hero is Antigone because she is willing to give her life for her principals and her love of her brother.