Final answer:
Gatsby and his guests' unknowingness about him serves to maintain his mystery and reflect the superficiality of the Roaring Twenties, emphasizing the personal yet universal nature of Gatsby's story as intended by Fitzgerald.
Step-by-step explanation:
The line about Gatsby and his guests paying "subtle tribute of knowing nothing about him" reflects how Jay Gatsby's mystique is maintained through the ignorance of his partygoers regarding his background and true identity. They enjoy his lavish hospitality without delving into his past or questioning the source of his wealth. This ignorance allows Gatsby's character to remain enigmatic and symbolizes the Superficial nature of the Roaring Twenties, where appearances were often valued over substance. In F. Scott Fitzgerald's narrative, this theme is illustrated through the focus on surface-level interactions and the suggestion that understanding someone's true nature was less important than enjoying the facade they provided.
Fitzgerald emphasizes the singularity of Gatsby's experience by suggesting his story is highly personal, rather than a general critique of the era's wealthy elite. The quote you've provided highlights that while Gatsby might be a stand-in for the typical rich man of the 1920s, he is at once both individual and universal, a symbol of broader themes and narratives of the time, yet unique in his personal triumphs and tragedies.