In the legend that I found, it gives the reason why there is a rainbow after a rainstorm. It starts with a star fairy being found at a riverside, with broken wings and unconscious. The woodcutter who finds her makes her makeshift braces for her broken wings, until she heals. Soon after, they fall in love, and get married. After they are married for a while, her wings heal, and she is taken up to her kingdom, as fairy and man can never be together. The two always go back to the river where they met, the man there physically, and the fairy watching from above. The fairy king takes pity on the couple, and whenever the rain stops, he allows the fairy to go down to the river to be reunited with her love.
In the story, it is set up by describing how the woodsman found the fairy, and where, and then talks about their love. This just sets up the story, and gives you information about why the king sent down his robes to make the rainbow; because of their love. Also, there were many different sentence lengths in the story, which helps make it not boring because when things are the same, it feels slow because of the lack of variety. The imagery also helps make a story interesting, because it helps you picture what was going on, like in the story, when the woodsman found his beloved fairy. It described his reaction and what he did to help her, and then later described their actions after they had been forced to part from one another, and how devastated they were. It was kind of really sad, tbh.
I think that the devices are important to stories because it helps tell it, and make it interesting. There is a big difference between “Jane likes to run,” and, “Jane loves the feel of the wind blowing through her hair as she sprints down the street, feeling the adrenaline running through her veins, and grinning with pleasure as she goes.” They both say the same thing, but adding those little details helps tell a better, more interesting story, which is why it is important for a writer to be able to add those things, the differed sentence lengths, details, and imagery. It tells a much better story.