How can Othello and Iago be seen as contrasting characters in Act 1 of Othello?I already have jealousy and race but is there more to it?

Othello and Iago have several elements to their characters
that indicate contrast. Iago is forthright to the audience in telling us of his
deceptive nature:

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 I am not what I am (I.
1)

In contrast Othello
believes that his deeds indicate his nature, as he says in Act I scene ii with regard to
the charges brought by Brabanitio for stealing his daughter
Desdemona:

‘My
services, which I have done the signiory

Shall out-tongue
his complaints. (I. ii)

Iago
judges all to be as deceptive and corrupt as himself, claiming both Cassio and Othello
have slept with his wife. However, he also says that Othello is much more trusting than
himself:

The
moor is of a free and open nature

That thinks men honest
that but seem to be so; (I
iii)

Othello on the other
hand believes faithfully in the good of others, most dangerously
Iago:

….my
ancient;

 A man he is of honesty and trust (I
iii)