Robin Hood, in my opinion, falls in to the definition of a hero. I think he would also be considered an anti-hero by others. The simple history of the character is that of stealing from the rich to give to the poor. For the poor that makes him a hero. Stealing makes him a thief and thus anti-hero to those from whom he took.
In the history of the period that the story is set in, the English Kings of the day, Richard the Lion Heart and his brother John, had run the royal coffers very low. That caused them to tax their citizens relentlessly. Historically, people in those days, with exception of the rich, had very little and survival was likely a daily struggle. The common folk could ill afford to support the royal houses. Robin Hood is the man that pilfers from the rich, giving the spoils to the poor and downtrodden; the hero of the day.
The story of Robin Hood is known around the world and resonates still today considering the current financial inequalities experienced by many. I think this tale will always carry some value to those who struggle. May the Hero live on!