Obviously, the boy is one of the main characters. He is likely at the center of the story's events.
Obviously, Harry Potter would be the main character. But the tigers that raise him would also be key characters in a sense. They would influence his growth and development. And then there would probably be other characters from the original Harry Potter series like Dumbledore who might try to reach out to Harry and bring him into the wizarding world properly.
The fat boy and the giant boy are surely the main characters. However, there could be other supporting characters that we don't know about yet. Maybe there are friends or foes of the fat boy and the giant boy that play important roles in the story as well.
Since I don't know the details of the 'lift boy story', the main character is probably the lift boy himself. There might also be other characters like the people who use the lift regularly, such as the building residents or office workers.
Since I don't know the exact 'owl boy story', I can only guess. There's probably the owl boy himself. Maybe there's an old owl who acts as his mentor, teaching him about the ways of owls.
Well, in a typical 'Wonder Boy Story', the main character would be the 'wonder boy' for sure. There might also be a mentor figure, like an old wise man or woman who gives him advice and guidance. And then there could be his peers, friends who accompany him on his adventures, sharing both the joys and sorrows, and together they face the challenges that come their way in the story.
The main characters are obviously the fox and the boy.
Obviously, the main characters are the boy and the starfish.
In a general 'stable boy story', the stable boy is the main protagonist. He may have friends among the other stable hands. If the story has a villain, it could be a competitor for a job or a person who wants to take over the stable. The horses are essential characters as well. Some might be old and wise, while others could be young and frisky. There could also be a character like a veterinarian who visits the stable and plays a role in the story, perhaps helping the stable boy with a sick horse.
Since I don't know the exact 'pea boy story', it's difficult to say. But surely the pea boy himself is likely to be a main character. There might also be his family members, like his parents or siblings, or friends in the story.
The obvious main character would be the paper boy. He could have a family, so his parents or siblings might be important characters too. For example, his father might be unemployed and the paper boy feels pressured to do well in his job to help the family. There could also be a rival paper boy in the area, competing for the best routes or the most customers, and this rival could be a main character in the story as well.