In the following excerpt from a novel, the protagonist reflects on their childhood experiences while sitting in an old, abandoned playground. The author describes the rusting swings, the cracked slide, and the remnants of laughter that echo faintly in the air. This setting serves as a vivid backdrop for the protagonist's thoughts on the passage of time and the lost innocence of youth. The author employs nostalgic imagery to evoke memories and feelings associated with childhood.
With this context in mind, what is the author’s primary purpose in using nostalgic imagery in this excerpt?