Rocky 

Diegetic Sound: The crowd cheers as Rocky punches Apollo and knocks him out.

Non-Diegetic Sound: The montage music of Bill Conti's "Gonna Fly Now" as Rocky trains for his fight.

Off Screen Sound: You are unable to see the commenters during Rocky's fight against Apollo, but you do    know that they are there in person (Diegetic sound), rather than a Non-Diegetic narrator.

The theme of Rocky is pretty simple; he doesn't want to be a loser anymore. Rocky's entire goal was to make something of himself. He didn't need to win the fight, that wasn't really he goal. He wanted to have the crowd cheering for him for once, and to find the love of him life. Rocky met his goal when he kissed Adrian after his fight and was told that she loved him.  

In 1975-1976, the idea of the underdog was becoming a big deal. People enjoy rooting for the underdog and to watch them come out on top.

Save the Cat: When Rocky was a loan shark, he refused to break the mans thumb or hurt him in any way. At another point in the movie, Rocky saw a man passed out in the cold, so Rocky carried him into the bar to keep him from freezing. From the very beginning, the audience fell in love with Rocky when he took care of his turtles and fish, calling them by their names, and moving the fish tank near the turtles so that  they could "interact" with each other.

Rocky is not an anti-hero. Even as a loan shark, he doesn't really seem like a bad guy. He's just doing what's necessary to get by. Rocky is nice, caring, and will never beat someone up if not in a boxing ring. Rocky refused to hit the guy paying back his loan, and wouldn't even hit his friend after he talked about Rocky having sex with his sister. Instead, Rocky got his point across by hitting the meat. I honestly don't believe that Rocky would truly hurt a fly outside of a boxing match.