For a lot of of anime, there seems to be a very clear line of what makes a hero; whether that be the person is predestine or just inherently good, there was is always an obvious difference. However, in reality there are more layers to distinguish the different types of heroes, and a majority of them aren't perfect. That imperfection in humans and heroes who happen to be humans is something that doesn't get explored too often, but I've seen two last season that did have their own ways of showing this.
Of course the most obvious, and the anime I've talked quite a bit, is Samurai Flamenco. When more of the heroic nature comes from a normal human who looks up to superheroes, and soon enough things take a turn for the worse. And the other anime is Yuusha ni Narenakatta Ore wa Shibushibu Shuushoku wo Ketsui Shimashita -- Yuushibu for short -- where the focus is on a fantasy setting where the greatest threat to humanity has already been defeated and the heroes are basically retired. Both have an interesting takes on the reality of what is required to be labeled a hero, and some people will do some shady shit to elevate them to such a position; that is I want to explore a bit more.
Not So Super
For the most part, Samurai Flamenco is set in a world absent of things like super powers. So trying to become something super takes a clear head and the ability to risk one's own life to change the world. So quite quickly we learn that someone like Maya Mari and the Flamenco Girls weren't that far up the justice tree to make the cut as heroes. And when things took a turn for the worse -- with the surprising appearance of a great evil like King Torture -- Samurai Flamenco was the only one, of the self proclaimed heroes, to be recognize as a threat to King Torture.
However, even being acknowledged as a hero in this type of setting, Hazama needed to remember that he is far from being "super". And what I mean by this is the fact that heroes usually get all the credit, but a lot of time there are a bunch of regular people that do some small amount of work to add up to be a significant amount of help to the hero. Really, even with King Torture being validation for Samurai Flamenco, we learned that everyone can be a hero, but not everyone will be appreciated -- and you doesn't necessarily need that super part in hero to be of any help.
Impure Motivation
Since most of the people that wanted to be hero could no longer become one -- because there was no 'evil one' to fight -- a lot of the people trying to become heroes turned to rather shady tactics in order to get what they wanted. Not only that but we found out a lot of heroes explicitly wouldn't defeat the demon lord for this big cycle of churning out "heroes" like a factory. Knowing their motives, it almost doesn't feel right to call them a hero because they just want it as a title and halfheartedly try to defeat something they never intend to defeat in the first place.
Their determination far extends the rationalization stage when they manipulated the former demon lord's successor -- that being Bloodstone Fino -- into becoming the new demon lord to fulfill their own fantasies. You would think a hero fights for peace, but the drive to be a hero flips the focus from the original goal to just wanting conflict, to continue being that hero they've dreamt of.
Revival
At the end of the day, most hero are in fact human and bound to human nature that can make them seem less perfect. I've always been of the mindset that any idol, hero, or any kind of role model doesn't need to be perfect -- and that is one aspect of these different perspectives of heroes. The other, that I mentioned during Samurai Flamenco section, is because many heroes are human, it is pretty obvious that there isn't anything special about the position. Anyone is able to get a shot if they wish, and some will fail, but the moral is that hero can be anything, including partly evil.