Powerpuff Girls (the OG) worked because it didn't back off from having the girls being highly competent superheroes while also being elementary school girls at the same time. One of the many reasons most women super heroes get a bad rep is because men writing women is laughably terrible. They have no idea how women actually act under crisis, leading them to write characters that buckle under pressure and are incapable of being autonomous (which is probably why so many basement trolls genuinely believe women are actually incompetent). They even call it out at one point when the girls decide to take up mantles of their favorite comic book heroes only to realize those heroes in a real life context would be laughably under prepared and most powers in comics have very little practical applications. Powerpuff Girls accepted that these girls who grew up with super powers would understand at least to an extent how to use them, and didn't question their abilities to save the day. Most episodes dealt with the girls dealing with realistic problems with the monsters an monster fighting as a metaphor for more abstract concepts that kids across the board dealt with. Crushes, bullies, bad words, curfews, even dealing with your parents dating someone less than stellar. The plots didn't rely on their gender as a plot point, but rather as a character trait.
