In any analysis relating to Othello as the main protagonist, one fact should stand central in our judgment—that Othello is an outsider. Once this fact is understood and appreciated, a true analysis of his character can be undertaken.
Venetian society was generally parochial. The Venetians were very keen to protect their morals, traditions and way of life from any external influence. As such, they displayed a certain level of snobbery, as can be seen in Iago's resentment that Cassio, a Florentine, had been appointed in a position which, he felt, he was more entitled and better qualified for.
In this scenario, then, Othello is introduced to us as a hero. He has overcome all the prejudice and has been given the highest honour—general of the Venetian army. Truly a remarkable achievement. We furthermore learn that he is not only a man of stature, but is also well-respected. He is welcomed into the house of Brabantio, a highly ranked citizen. We see from the duke's reticence to pass summary judgment over him as an indication of the esteem in which Othello is held.
We also learn that he is an experienced soldier, battle-hardened and one who has overcome many trials. Othello is of a different racial persuasion than the general Venetian populace, which makes his achievement even more exceptional. Othello is also not afraid to be further entrenched in Venetian culture and custom, for he takes a tremendous risk in eloping with Desdemona, a Venetian. To add to this, he is also much older than her, indicating that he was prepared to lose all he had gained to be with his one true love. This act, in itself, gains our admiration.
We know that Othello is also proud. for he speaks with authority about his prowess as a soldier and of his royal history. He is also humble, for he tells his audience (during his interrogation by the duke) that he is not a great speaker, but when he does speak, his eloquence is impressive. It is this talent which moved Desdemona to tears and inflamed her desire to be with him.
However, all this quickly unravels once Othello allows himself to fall victim to Iago's malicious manipulation. Our hero soon devolves into an anti-hero. We discover that Othello has issues which Iago gleefully exploits. We learn that he is insecure about his foreign status, his age, his race, his poor knowledge of Venetian custom and probably also the fact that he suffers from an uncontrollable ailment—seizures which are exacerbated when he is angered or stressed.
Our hero's feet of clay gradually crumble until they are nothing. Iago's persistent chiselling at Othello's ego brings out the worst in him. We discover that he is deeply jealous. He overreacts at Iago's initial subtle suggestions that Desdemona and Cassio are involved in an adulterous liaison. Although he confidently asserts that she had chosen him over all the other handsome Venetian men who were vying for her attention, there is a slight hint that he has been unnerved. Proof of this is when he insistently asks Iago questions about what he is implying when he, for example, after seeing Cassio slink away 'guilty like' from Desdemona's company, states, 'I like not that.'
The pernicious Iago sees his advantage and Othello becomes like putty in his hands. Iago is in full control and we feel pity for him but are, simultaneously, angry that he, a man of such stature, could be so feeble-minded and gullible as to bend to Iago's malevolent machinations.
In the end, Othello tragically becomes a victim of his own uncertainty. Although he had overcome so many tribulations, he is finally beaten by the fact that he could not overcome the one thing that stood between him and true love, acceptance and security: he was an outsider.