Life has the same value regardless of how many people live in a town.
By heralding the small towns of Canada, Leacock shows a version of small town life that has charm and vibrance, even humor. He even argues that the center of the political debate of Canada was in his little fictional town. This is an argument against the dominant city assumption of small towns that small town life must be dull or unpleasant.
People are interconnected.
There's no getting around this aspect of the stories. Since they each use the same cast of small town archetypes, the stories are intertwined, showing how integral relationships are to life, and maybe even drawing attention to the fact that when a town is small enough for people to know everyone else, that a special kind of levity and communal feeling arises.
People are dramatic.
Look at Zena Pepperleigh, the romantic interest of a Mr. Peter Pupkin. By showing Pupkin's affections for Zena, Zena is made into a romantic character. Her primary character device? That she loves romance novels.
This redoubling of typical small town roles occurs for many characters, and the effect is that the characters are charming role-players. But it seems that for many of them, having that sense of communal identity in place is actually meaningful in its own right.
Small towns aren't a small part of the population.
This is made explicit when Leacock states outright that Mariposa is not a real town, but rather, it's a typical Canadian town. He then notes that there are many, many communities like Mariposa in real life, drawing attention to the stories of what some might call "Flyover land."
