Stallone himself spoke about the Raging Bull comparison and he said Bull is about a real fighter while Rocky is a metaphor. That's why Rocky opens (Stallone says) with a shot of Jesus over the ring. Rocky is one of the downtrodden, invisible masses but he has a destiny to accomplish - a higher calling he doesn't even know about.
Along the way he encounters a lot of resistance and hostility. Rocky and the people in his life are all broken and frustrated. Rocky is always being insulted and dismissed. Mick calls him a bum who fights like an ape. A young girl he tries to help gives him the "up-yours" sign. A fellow fighter at Rocky's gym tells him how much he likes Rocky's locker after he got after Mickey who took it away from Rocky.
Even Gazzo's driver hates him but Gazzo tells Rock "Some guys they just hate for no reason." Rocky on the other hand is not like that. He does bad things to survive but its just "work" he needs and his heart isn't in it. He's always trying to do good without thinking about it. He's walking down a street and picks-up a drunk passed out on the sidewalk. Most people wouldn't even notice the guy but Rocky helps without giving thought.
In the end when he survives the fight he doesn't even care. Apollo wins but Rocky takes him the distance for the first time. Rocky wins over himself by doing more then he thought he could - surviving.
I always find the love story and the Pauli stuff a drag but they represent a group of unrealized souls with various torments. The construction of the film makes up for it
This is how you win Oscar for editing - Gazzo spits in a long shot.
Then comes a medium shot with Gazzo wiping his mouth after the spit.
Subtle but very smooth transition - clever - the whole film rolls like that