Merchant of Venice play without a hero. Discuss

In order to have a hero you have to have a main character who faces and ultimately overcomes a challenge. No one character stands out in that role. Shylock, for example. faces a challenge, but he acts in such a "non-heroic" way that he cannot be considered a hero. The way in which Portia saves Antonio's life, while noble, is not heroic and is based on the fact that she is intelligent and clever. Antonio, who signs Shylock's contract to help his friend, is a "good guy" and certainly noble, but again is not facing a challenge that he conquers on his own.