One of the things that William Faulkner excelled at was exposing human character through his stories and A Rose for Emily was no different. One of the first and most powerful truths about humanity that the reader finds is the willingness, even eagerness of humans to judge one another without knowing enough to make a fair judgment. The town is quick to judge Emily without knowing her whole story, in fact knowing very little about how she ended up in the situation she did. But their assumed superiority, their righteousness is affronted at the choices she is making and they take it upon themselves to "do something about it."
Another truth about humanity is the ubiquitous desire to love and be loved. Miss Emily had suitors turned away by her father and now finds herself alone and without much prospect for a suitable match. The fact that she keeps the body as an extremely odd way of alleviating her loneliness serves as an example of how powerful this desire for companionship is.