Even a noble and heroic person can fall into depravity and ruin
Macbeth is about how blind ambition can lead to the downfall of even honorable people. Macbeth and Lady Macbeth are tragic heroes in the play; they show that things could have ended differently only if they made different choices.
Lady Macbeth felt guilt toward the end, and Macbeth faced Macduff even though he knew he would probably lose the fight and die as a result.