Herobrine was never real. Its origin was from a livestream that I don't remember the name of where these guys were building a house and opened a door where they found herobrine in that room. They quickly closed the door a ran away. Later they admitted that it was fake and all a joke.
Notch even confirmed that he didn't add him and he was never going to. People had already made a creepypasta about herobrine how he was his dead brother and that stuff.