Great question. The first description, though, isn't scenery so much as it is the vivid and intense life of the animal kingdom. Compare that to the start of Chapter 13, when Tom is gloomy and friendless (at least in his own mind). Chapter 13 gives us isolation as loneliness. Chapter 14, by contrast, shows us the wonder and activity of nature. There is an entire society there that Tom hadn't paid attention to. It is a great thing in itself, a kind of wonder he'd never had seen if he'd stayed in normal human society. However, it is also more than that. It is evidence that others can create fun and lively societies outside the boundaries of the town, and, just as these bugs and others do, so Tom can (and be a pirate!).