Since I don't know the specific 'pond life novel', I can't say for sure. But it could be the animals living in the pond like a wise old turtle or a curious little frog.
The main characters in a 'pond life novel' could be diverse. There might be a family of ducks that are always looking for food in the pond. Or perhaps a heron that stands majestically by the pond side, being a somewhat mysterious figure in the story. There could also be a group of water beetles that are constantly scurrying about, and they could play important roles in the overall plot, maybe they are the ones who first notice something strange happening in the pond environment.
In the 'life in a pond story', the main characters could also include the insects that live near or on the pond. Dragonflies, for instance, start their life in the pond as nymphs. Their presence affects the pond's ecosystem and they are an important part of the story of life in the pond.
Probably the fish are the main characters. They are often a significant part of pond life.
I'm not sure as you haven't provided the actual story. But usually, there could be a local who has a special connection to the pond, like an old fisherman.
Since I don't know the exact story, it could be the miller. He would be a key figure as he operates the mill by the pond.
As I don't know the details of the story, it's hard to say. But most likely the kid is one of the main characters. There could also be other characters like the kid's parents if they play a role in the events related to the pond, or perhaps some local people who know about the pond's reputation.
I don't know the exact story, so it's hard to say. But it could be the local people who live near the pond.
The main characters are, without a doubt, the little frog and the small pond. The frog is the protagonist that we probably follow in the story. It may swim in the pond, sit on the lily pads in the pond. The small pond is the context within which the frog exists. It's the stage for the frog's activities, and it shapes the frog's life in the story.
It's possible that there is a group of people rather than just one main character. For example, a community living near the pond full of milk. Each member of the community might have different reactions and ideas about the pond, and their interactions could drive the story forward.
I'm not sure specifically as there could be many novels related to 'pond life'. It might be about the various organisms that live in a pond, like frogs, fish, and insects, and their daily interactions and life cycles.