Wikipedia says
A superhero or superheroine is a stock character that typically possesses superpowers, abilities beyond those of ordinary people, and fits the role of the hero, typically using their powers to help the world become a better place, or dedicating themselves to protecting the public and fighting crime.
So yes, he is definitely dedicated to protecting the public, but it feels wrong to call him a super hero. What do you think?
Gandalf isn’t a superhero because he’s more like an angel. He played a part in the creation of the world, and is entirely inhuman. He’s a primordial spirit masquerading in a corporeal form.
Luke Skywalker is much closer to a superhero because he’s a mortal man who was inadvertently blessed with incredibly rare powers and chooses to use them for good.