I don't have enough details about 'the little story' to say for sure, but it could be a child, a pet, or an old wise man.
In the chicken little characters story, the key character is Chicken Little, the one who believes the sky is falling. Another important character is Foxy Loxy, a rather sly animal. There are also other barnyard animals like Henny Penny and Ducky Lucky who are involved in Chicken Little's adventure when he spreads the word about the sky falling.
The main characters of 'little busters main story' are the boys and girls who form the Little Busters. Riki Naoe is a central character, being somewhat of a narrator in a way as we see the story through his perspective at times. Kyousuke Natsume is a charismatic figure in the group. Then there are other members like Masato Inohara and Kengo Miyazato. The female characters such as Rin Natsume also play significant roles in the story, adding different dimensions to the relationships and the overall plot.
The main characters are obviously the little boy and the little cat.
The main characters are Little Grey and Little White.
The main characters are Little Fred and Little Buck, of course.
In the 'little pig little pig story', the key characters are, of course, the little pigs. There are usually three of them. Each pig has its own personality which is reflected in how they build their houses. And then there is the big bad wolf. He is the antagonist. He is very sly and tries to catch the pigs for his meal. These characters together create the classic plot of the story.
The main characters are Little Blue and Little Yellow. They are the ones who go through various experiences in the story like playing together and getting all mixed up.
The story mainly features Little Blue and Little Yellow. They are the central figures around which the whole story revolves. Their interactions, like playing together and hugging, drive the plot forward.
Not having read the 'little by little 5th grade story', it's hard to say exactly who the main characters are. However, in a typical 5th grade - centered story, we might expect to see a young protagonist, perhaps a boy or a girl who is dealing with the typical issues of 5th graders like homework, friendships, and getting along with parents. There could also be side characters like the school bully, the kind librarian, or the strict principal that play important roles in the story's development. But again, this is just a general idea based on what we might expect from a 5th grade story.
In this unknown 'the little boy story', aside from the little boy, there could be a wise old man in the neighborhood. The old man might act as a mentor to the boy, guiding him with valuable advice through different situations in the story.