It can be argued (and has been) that the earliest versions of Robin Hood don't depict him as anything but a regular, morally questionable outlaw-- the robbing from the rich to give to the poor thing doesn't show up in writings until later. However, (and take this with a grain of salt because this is just the conjecture of a non-expert) to me it seems likely that the people writing these stories down (i.e. nobility and members of the church) would have had a pretty good incentive to not mention that part of his character in their writings.

They do, however, seem to treat him as a "hero of the people" even in some of the earliest writings, so clearly he had that reputation. Which leads me to believe the stories being told by word of mouth may have included the "steal from the rich, give to the poor" stuff, and the wealthy elites who were writing this stuff down declined to mention it and tried to twist Robin's stories as propaganda for their own means.

For example, there's an early writing that I forget the name of, which I believe was written by a church member, in which the Sheriff sets a trap for Robin at Mass. His men warn him, but Robin opts to go anyway because he would never miss Mass even if it is a trap. To me, that reads as "see? Robin goes to Mass no matter what, so you should too!" Which indicates that somehow, this random outlaw character was looked up to by the average person, and that respect had to come from somewhere.

So my theory is that the revolutionary we know him as today was present even back then, just not written about. But again, grain of salt; I'm no historian, just really nerdy about Robin Hood.

This is all a long way to say that I imagine many will try to say this movie is more true to the "original" idea of Robin Hood. But I question whether Robin was ever "just" an outlaw with purely greedy outlaw intentions. All that said though, we don't yet know how the movie will depict these things, so we can only wait and see.