The conceited little rat is the main character in this story. It's the one around which the whole narrative revolves. There could be other secondary characters like other animals in the rat's environment perhaps, but they are not the main focus. The story is mainly about the little rat's conceited behavior and what happens as a result of it.
Obviously, the central figure in the conceited little rat story is the little rat itself which is conceited. There might not be other clearly defined main characters mentioned, as the focus is on the rat's conceit and whatever events unfold around it because of that trait.
The moral could be that excessive pride leads to downfall. Just like the conceited little rat, when one is too full of themselves, they may overlook important things and make mistakes.
Since it's the 'king rat story', the main character is likely the king rat itself. There may also be other rats in the story, like his loyal subjects or rivals.
In the 'kid and rat story', the two central figures are, as the name suggests, a kid and a rat. The kid could be a young boy or girl, and the rat is the other important entity in the story. Their actions and interactions form the core of the story.
Since we don't know the exact 'rat man story', it's hard to say for sure. But likely the main character is the 'rat man' himself.
In the 'rat king story', the main characters are, of course, the rats that form the rat king. There might also be humans who discover or are affected by the presence of the rat king in some versions.
Since I don't know the story, I can't be sure. But I guess the main character is Rat King Little King.
The two main characters in the 'lion and the rat short story' are, as the name suggests, the lion and the rat. The lion is this majestic, strong beast that dominates the forest. The rat, on the other hand, is a tiny creature that scurries around. But their encounter and the events that follow make them the central figures in this story. The lion's initial dismissal of the rat and the rat's later heroics create the plot's main arc.
In the cat and the old rat story, the central figures are the cat, which represents a threat, and the old rat. The old rat has to use its intelligence to deal with the cat, so these two are the main characters in this narrative.
Since I don't know the exact 'the rat catcher short story', but most likely the main character is the rat catcher himself. There might also be rats as sort of secondary characters that play an important role in the story.
The main characters are obviously the rat and the cat.