Good, great, hero.
A good person is someone who helps others if they see something they could help with. Like volunteering at the local homeless shelter, or donating a little bit of money.
A great person is someone who goes out of their way to find someone in need of help, and then helps them. And if they see any random person who wants to be saved, or be fed, or hydrated; and any number of other things, then they will go out of their way to satisfy them.
But a hero? Well, a hero won't stop at just looking for someone who needs help. Donating all of their money besides what they need to live; moving to another country just to offer their skills or services; bringing hope to a child, without any trickery.
Everyone can be a good person. Some people are great. But a hero? Only a few people are that amazing.