This play is not so much about Italians as it is about white Christian Europeans in general. Remember, it would have been staged in England, so nationality is not as important as race and religion. Plus, Venice is a city-state with its own government, army, and economy, and not representative of Italy as a national power.
At the time of the play, 1600, the slave trade was beginning in Europe that would racially divide the world for 400 years. Before this, Christendom battled the Moors, whose religion is Islam, for several hundred years before finally defeating them some time in the 15th C.
Act I takes place in Venice, a city-state in Italy, but it could have just as easily been set in Greece or Spain or some other country on the Mediterranean Sea. Shakespeare chose Venice because it was a cosmopolitan city with a vibrant trade, and it was at war with the Turks (Muslims).
Brabantio, a senator there and Desdemona's father, reveals a racist attitude against the Moors (namely Othello), while the Duke of Venice reveals an open and trustworthy attitude toward him. Both men are afraid of foreigners: Brabantio psychologically, and the Duke militarily.
Brabantio says in Act I:
and Iago says:
Because we come to
do you service and you think we are ruffians, you'll
have your daughter covered with a Barbary horse;
you'll have your nephews neigh to you; you'll have
coursers for cousins and gennets for germans.
These quotes reveal the two great fears in the white Christian world of 1600: fear of black men stealing their white women, and the fear of Islam replacing Christianity.
The Duke, on the other hand, is very fair to Othello. He promotes him to general and condones the marriage to Desdemona. (This, of course, would never have been sanctioned by the state). He says:
and after Othello's long monologue, the Duke says of Othello:
In Act I of Othello, Shakespeare shows both white against black racism (realistic at the time) and racial acceptance (ahead of its time).