Heros and Villains are but a social construct. We only see heroes and villains based on how we were raised.

Let’s look at legend of korra for example. It has a great selection of complex characters.

Amon was right in that there are benders who use their bending to harm those who cannot bend. He was right in that there should be equality among the people of the world.

Unaloq wished to bring balance between the spirit world and the human world. He wished to break the illusion of separation. 

Zaheer took down a corrupt leader but in doing so, he spread chaos.

Kuveira wished to bring the order back to the kingdom.

These are the “villains.” Now, let us look at the “hero.”

Korra in season one didn’t do much but in season two, she opened up the portals which led Vaatu to “kill” rava and disconnect her from the previous avatars. Essentially killing every avatar before her and starting the cycle anew.

After season two, she caused one of the most dangerous prisoners to gain the ability to escape and let the spirits cause chaos in the world.

After season three, she was absent and that led Kuveira to be put in charge of cleaning up Zaheers mess.

All of the biggest problems were because of korras actions in season two and yet she is still the hero.