The main characters are the boy and the rooster, of course.
Obviously, the little rooster is one of the main characters.
The main characters are the fox and the rooster, of course.
Since I don't know the exact 'black rooster story', I can't say for sure. But it might have the black rooster as the main character, and perhaps there could be other animals like hens, a sly fox, or a kind old farmer.
Regarding Rooster Teeth Animated Stories, in 'RWBY' the main characters each bring something unique. Ruby with her determination to be a Huntress, Weiss with her elegance and combat skills, Blake with her mysterious past, and Yang with her strength. In 'Red vs. Blue', Church is the central figure in the early seasons, his sarcastic and sometimes confused nature driving the story. Tucker provides a lot of the humor with his womanizing ways and Caboose is the innocent - but - dangerous type. In 'Camp Camp', David is the heart of the story, constantly trying to make the camp a positive experience for the kids while dealing with their antics.
The moral could be about the importance of understanding the right time for things. Just like the rooster crowed at the wrong time and got into trouble.
Other than them, there could be new characters created specifically for the fanfic. These might be other pilots in training with Rooster. They could be his rivals, constantly trying to outdo him in training exercises, or they could be his allies, working together to solve problems and complete missions.
In the 'The Boy and the Rooster' Chinese story, the moral could also be about responsibility. If the boy is in charge of the rooster, he has a duty to take care of it. This could involve feeding it, protecting it from harm, and providing a proper living environment. Through his experiences with the rooster, he learns that being responsible is important. For instance, if he forgets to feed the rooster one day and the rooster gets sick or weak, he realizes that his lack of responsibility has negative consequences, and thus he becomes more responsible in the future.
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 specific 'boy brides story', I can't tell who the main characters are for sure.
The main character is the shepherd boy. And the villagers are also important characters in the story.