Sol here, I have returned, and now I'm going to talk about Main Characters, but also 'heroism', mainly, how to tell when a hero is done well.
This should be simple, its the main character. This person is the one whose perspective we mainly follow for the story, and who generally gets the most character development. That last part is often why Ultras with human forms are often considered better heroes than Ultras with human hosts, because in the later part, the characterization and character growth of the civilian identity and hero identity are often separated, unless you're X and you actually get to talk to people.
However, one thing you should note, while in Ultraman, the protagonist is typicaly the hero, Protagonists are not always heroic.
Now if we want our Protagonist to be heroic, let's come up with a standard definition, by which we can judge this. Let use the adage 'People are define by their problems, Heroes are defined by how they deal with their problems.'
This is true, all the best heroes, good heroes have a sense of agency. They don't wait for their problem to be solved, they work to solve it. This is the difference between a damsel in distress and a female hero. One is really just reward of the quest, the other is someone on the quest.
You can see this with Ultramen, regardless of whether it's a human host or form, you rarely see a main character not ready to try and solve the problem, even if we do see newbie jitters once in the beginning. Which is why I get annoyed with the ending of Ultraman Jack. In that ending, the writers did the most unthinkable thing you could do with an Ultraman...worse than Dan being uncharacteristically mean in Ultraman Leo (do be fair, that instance of him was originally supposed to be another character altogether...) at the end of Return of Ultraman...they made Jack afraid of Zetton...
This is not like in Mebius when he was afraid of Bemstar due to all the stories he heard about that monster, Mebius still showed up for the fight. No, they straight up had Goh attempting to transform, and Jack refused because he was scared...they literally had Ultraman...hiding inside his host.
Now the idea of Ultraman being afraid of a monster...is not a problem, if it is done correctly. It was done well with Mebius and poorly with Jack, and the reason for this is, Mebius was shown dealing with his problem, his fear. Jack just transformed and anti-climatically destroyed Zetton. Jack's sense of agency, his defining trait as a hero, was taken away from him. Ultraman, in this case Jack, was, for that period of time, stripped of his nature as a hero, and reduced to someone that had to be saved, because Alien Bat and Zetton were after him. Never do this without a good, justifiable reason, otherwise, this is what we call character suicide.
If they had made it that Bat had generated some sort of field, that stopped Goh from transforming, or that Jack sensed a trap and was waiting for the right time to step in.
Now, one must ask, what makes an Anti-Hero so different from a hero. Then answer is found in what makes them 'heroes', in the context that this blog is using. Heroes, solve their problems, but traditional heroes, do so in away that is meant to be awe inspiring. When heroes solve their problems we are supposed to respect them for it. Anti-Heroes solve their problems in way that may not be...moral.
An anti-hero may have the same, or a similar goal as the hero, or simply not have a villanous goal, but the means by which they go about solving their problems, may result in people getting hurt, people being used. They are solving their problem, but the way they do it, may involve methods we cannot agree with.
This is here mainly because I know some fool is going to ask...and I'm not being general, I do have an idea of who would ask me (don't ask I'm not going to give names). In short, a female hero is a hero...who is female. This is not difficult, this is not a complicated topic, it's a female character, who has a sense of agency in the story. She has problems, she goes out and solves them. She can be a hero, or an anti-hero, doesn't matter, even if she isn't the main character, she's just not a damsel to be rescued.
If this is beyond you, if the idea of a 'female' hero or protagonist seems so strange, alien to you, so absurd...yeah you're sexist.
Heroism comes in many forms, and many people have their own definitions, but all heroes share something in common. Whether they be simple everyday heroes, super heroes, anti-heroes and whatever other term has 'hero' in it, they all have agency in their story, they are not the characters on the sideline. That is unless you're going through a hero's journey sort of story, in which case, yes they can start out this way, but by the end, maybe even the mid point of the story, they should have grown into a sense of agency.
Now your hero doesn't not have to be universally competent, that's just making them OP, but making them entire helpless is not the way to go.
Also note, this blog is not to define 'heroism', it's to define 'heroic' as a trait for your character(s).