how can people say they wouldn't or couldn't do it?
Either you and everyone else dies, or you die and you save hundreds of people.
This is what defines the kid as a true hero. When faced with a life or death situation, the body's "fight or flight" response kicks in. Fear of death kicks into overdrive and causes the mind to focus on self preservation over self sacrifice. Overcoming such fear to save others is the purest essence of bravery.
This kid demonstrated that and is a hero in the truest sense.