Han Solo is exactly the opposite of a hero, he does whatever it needs to be done. And that's the difference between him and an ordinary hero. He doesn't explain his ways, doesn't tell all his secrets, doesn't have family issues. He got the hero's sister. He doesn't show up when everybody is counting on him. He does it when it's necessary. And the most important part: his partner is the all times beloved Chewbacca. Who needs to have deeply moral and ethics, when you're the most badass in an epic trilogy?
He explains how to live, never teaching, but living this way. And that's why he is awesome.