I think if you take a look at the protagonists as listed above, they have a moral attitude. They hope to see truth and goodness prevail. They do not try to hide behind any kind of face or presence or reputation, they are just themselves and find value in who they are. These characters are open-minided allowing for a variety of perspectives. They appreciate all people for who they are.
The antagonists selfishly concern themselves with appearances and reputations. They believe things should be a certain way and no other way seeing the world truly from their own perspective and set of beliefs however ill-founded they might be.
In To Kill a Mockingbird, depending on how you look at it, the protagonists are Scout and Atticus--Scout in Part I and Atticus in Part II. The antagonist is Bob Ewell, although we think it is Boo Radley in Part I at least.
The protagonists believe in:
- SOCIAL GOOD
- SOCIAL EVIL
- CHILDHOOD INNOCENCE
- RACIAL/CLASS EQUALITY
- EARLY FEMINISM
While the antagonist believes in:
- SOCIAL EVIL (INTIMIDATION)
- RACIAL/CLASS PREJUDICE
- WHITE TRADITION
- NO LAW
- SOUTHERN BELLE & ("LADY-LIKE") ATTITUDES