Every character struggles throughout the book. That is what makes it dramatic. Obviously Tom Robinson is the most tragic character. He is a good man who is wrongfully accused, because of his race and the backward ways of his young accuser.
Tom Robinson is a good neighbor and friend to Mayella. His only crime is that he felt sorry for her and admitted it in court. That was the beginning of the end. It was all the jury needed as an excuse to convict him.
The witness realized his mistake and shifted uncomfortably in the chair. But the damage was done. Below us, nobody liked Tom Robinson's answer. Mr. Gilmer paused a long time to let it sink in. (ch 19)
Tom Robinson is not guilty of raping Mayella Ewell. Atticus proves that. Instead, he is guilty of putting himself above a white woman. As a black man, he is supposed to humble himself and not consider himself her equal.