In the 'selkie children's story', the central character is the selkie child. This character is what drives the plot forward. However, depending on the specific story, there could be other important characters too. For example, if the story is about the selkie child being captured by a human, that human would be a significant character. Or if there are other magical sea creatures that help or hinder the selkie child on its journey, they would also be main characters in a sense.
The Selkies themselves are main characters. They are the ones with the ability to transform. And the humans who interact with them, like the fishermen or the ones who fall in love with them.
In the 'the selkie girl story', the most prominent characters are the selkie girl, who is a magical being that can transform from a seal to a human. And then there's the human male who plays a crucial role. He takes her seal skin, which is a key action that drives the whole story. Without him taking the skin, the story wouldn't be what it is. There could also be other minor characters in some versions, like the man's family or other villagers, but the selkie girl and the man are the central figures.
A selkie story often involves selkies, which are mythical creatures that can transform from seals to humans. In a selkie children's story, it might be about a selkie child who gets separated from its family in the sea. Maybe it gets caught on land by a fisherman or a child on the shore discovers it. There could be adventures as the selkie tries to find its way back home, or it could form an unlikely friendship with the humans it meets along the way.
I don't know for sure as I haven't read it, but likely there would be a selkie as one of the main characters. And probably a human who becomes involved with the selkie, perhaps a fisherman or a coastal dweller.
There's no way to tell without more details about the story. However, it could be that the main characters are a couple of adventurous children. One might be a curious little boy who is always getting into trouble, and the other could be a smart girl who helps him out of jams. And the meatballs are somehow central to their adventures, like they are searching for the secret ingredient for the best meatballs ever.
The main character is Thumbelina, of course. And there are also a toad, a mole, and a flower - fairy prince.
In the 'Sabbath Children's Story', it's possible that the main characters are children from different backgrounds coming together to experience the Sabbath. There could be a curious child who asks a lot of questions about the Sabbath, an older child who acts as a role model in following the Sabbath rules, and perhaps a kind-hearted elder in the community who shares stories and wisdom related to the Sabbath with the children.
The primary characters in the Children's Pentecost story are the apostles. These were the men who followed Jesus and were waiting in Jerusalem as instructed. When the day of Pentecost arrived, they were in a room together. Then, the Holy Spirit came upon them. They became the focus of this amazing event as they were filled with the Holy Spirit, and their lives were changed. Their experience of the Pentecost is what the story for children is mainly about, and so they are the main characters.
The main character is surely the ladybug. Depending on the story, there might be a friendly spider that helps the ladybug at some point, or a mean wasp that tries to bother it. There could also be a little boy or girl who observes the ladybug's activities, which would make them a part of the story too.
As I don't know the 'balleneria children's story', I can't tell who the main characters are.