We learn several important points about Maycomb though the trial of Tom Robinson.
First, we learn that most of the people in Maycomb do not really care that justice is done. When Tom is charged with rape, the majority of the people in Maycomb (at least the whites) do not care about their truth. They will simply side with Mayella, because she is white. And Tom is guilty, because he is black. So, much of the town is seriously racist. For instance, Mr. Cunningham and a mob of people come to harm Tom while he is in prison. They were even going to harm Atticus.
Second, there are some in the town that do care about justice, but they are a small minority. Atticus is the obvious example, but there are others such as Ms. Maudie, Heck Tate, and a few others. But this minority does not really have a voice.
Finally, you also have the black community. For the most part, black characters are interested in justice and value human life, like Calpurnia and Revernd Sykes. They are kind, sacrificial, morally upright, and stand for justice.