Seeing Holden Caulfield as a hero is tough. Really tough. For most of the novel, I wanted to throw Holden out of a window or something. He complains about everything, and he is never willing to do anything about his complaints. Additionally, Holden is nothing like a typical noble hero. He's not honest. In fact, Holden is a perpetual liar. For example:
"Oh, how nice!" the lady said. But not corny. She was just nice and all. "I must tell Ernest we met," she said. "May I ask your name, dear?"
"Rudolf Schmidt," I told her. I didn't feel like giving her my whole life history. Rudolf Schmidt was the name of the janitor of our dorm.
There is literally zero reason for Holden to lie here. He's not in trouble, and saying his real name would carry no consequences, yet Holden lies about it.
Holden is also not a typical hero, because he's not brave either.
I'm one of these very yellow guys. . . Only, I wouldn't have the guts to do it. I'd just stand there, trying to look tough.
Finally, Holden is not a hero because he's completely incapable of making any kind of authoritative decision.
Like I said, it's tough to see him as a hero. I've read a character analysis or two that says that Holden is a hero because he is the protagonist. That's ridiculous, but I can find a way to see Holden as a hero character. Holden can be viewed as a hero because Holden cares deeply for people that are close to him. Take Jane, for example. Holden can't screw up the nerve to do anything about his own feelings for Jane, but Holden most definitely wants to protect her from guys like Stradlater.
"You don't even know if her first name is Jane or Jean, ya goddam moron!"
Holden is equally protective of his sister too. I don't know if Holden would have followed through with leaving town, but I do believe that the main reason that Holden didn't leave is because he wants to be there for his sister. That's honorable and heroic in my opinion.