In the beginning of the play, he is considered a man of pride who values friendship and honor. It is agreeable that he is a "good person" for many reasons, one being that he has lot of trust for a lot of people in the play. Sadly, he misplaces his trust towards someone who he thought was loyal to him, which of course takes Othello down the wrong path. Despite the fact that not everyone liked him the way he wanted to be liked, he was still the bigger man who put everything behind him. Even when Brabantio doesn't like the fact that Othello had married his daughter, he still treats Brabantio with respect. He is a good person, because he had pure love for Desdemona, but Iago's selfish actions made Othello doubt his love for her. Even when he kills his wife because of something he accused her of doing, he still holds respect for her. An act of respect for her is when he is preparing to kill her. He mumbles to himself in the dark while Desdemona is on the bed and says, .
"It is the cause. Yet I'll not shed her blood,.
Nor scar that whiter skin of hers than snow,.
And smooth as monumental alabaster.
Yet she must die, else she'll betray more men" (V.ii.3-6).
If Othello was an evil man, he would be insulting his wife instead of saying how he doesn't want her beautiful skin to be messed up by blood. In the same scene, he suggests her to pray for forgiveness for any crimes she hasn't confessed. When she asks him why he wants her to pray, he says, "Well, do it, and be brief; I will walk by. I will not kill thy unprepared spirit. No heavens forfend! I will not kill thy soul" (V.ii.32-34). Because Othello is a good man, he tells her that he doesn't want to send her soul to hell when he kills her. With all the evidence revolving around respect, it is agreeable that he is considered a "good man".
Hamartia is a fatal flaw that leads Othello to his downfall. In this play, Othello's hamartia is jealousy.