Would you consider the Mirage TMNT as heroes?
 

Olga booga

Not at all, not vigilantes and certainly not "superheroes."

Never considered them as traditional superheroes, like Batman and Spider-Man, which influenced me a lot, when I writing characters of my own.

They are more vigilantes / volunteers to me. It goes for basically any version of them.

Their vigilantism is incidental, though, at best. There is no notion of, "We need to go out there and fight crime for a society we have nothing to do with!" Because that's stupid and doesn't make any sense.

If someone is being robbed in front of them, would they stop it? Probably. Might they be encouraged to occasionally look for criminals to beat up for training purposes? Eh, maybe. But that's about it.

Indeed.

For my own characters, they are almost always motivated by their own personal reasons or just being agents working for some organization. Though they can be vigilantes as well.

No, but City at War touched on this topic a bit. Not just "are they vigilanges?", but what is their purpose in general, and what holds them together.

That was the perfect story for Mirage volume 1 to end on.

No. They're ninja. Trained killers/assassins. Their goal was to end the Shredder though so everything after that is just doing whatever it takes to survive.

They are no heroes, just a bunch of unluky but resilient freaks.

Nah, they're mostly fighting to survive the insane situations they end up in, and unlike most of them, they not only NOT develop into heroes over time, but have done some things for reasons that are rather unheroic.