The answer to the question posed here is simply this:
Three of the characters referenced are artificial beings who possess, through whatever comic-book magic, human-like sentience. Even a comics-fan of modest knowledge should probably know that the three referenced are the original Golden Age Human Torch, the Vision of AVENGERS fame, and the manga-born Cutey Honey.
The other three-- Electro, Gigantor, and the improbably named Bozo the Iron Man-- are all robots in human form, but without any trace of sentience. If they are focal presences, then they are such in the same manner as the nearly-unseen phenomenon of "The Crazy Ray" seen in the movie of the same name, discussed here.
Nevertheless, just as a mass of crazed radiation is more the star of that film than the negligible viewpoint characters, the three non-sentient robots are both the focal presences and the "heroes" of their respective narratives. A well-concieved list of heroes within the superheroic idiom will include Gigantor, not his teenaged controller, who in American markets went by the name of Jimmy Sparks (seen here performing what looks like a Hitler-salute).
This does not mean that the non-sentient mechanical creation is always the star of the show. A counter-example would be the Mach 5 of SPEED RACER fame. In some ways this fantasy-vehicle is used to evoke wonder as is the power of Gigantor, but on average the narrative of the SPEED RACER manga and anime place far more emphasis on the heroic driver himself.
More on this distinction later.