The underlying thematic elements of fairytales, as evident in Tolkien’s and Lewis’s works, contribute to ideas about the nature of human will, which can overcome obstacles via its intrinsically good, innocent and resilient nature. That’s the portrayal of the ideal human will.
It’s also why you often see fairly tales across cultures carrying some message of hope and optimism, regardless of how they “end”.
But actually, in essence a fairy tale never ends because those who read it or hear are supposed to be changed by having done so, and they carry what they take from it with them. Here is where you often get a connection between fairy tales, folk tales, traditions and cultural myths.