What Does Nick Mean By The Last Line Of The Great Gatsby?

The last line of "The Great Gatsby" by F. Scott Fitzgerald, "So we beat on, boats against the current, borne back ceaselessly into the past," has been interpreted in various ways. The narrator, Nick Carraway, is reflecting on the events of the summer he spent with Gatsby and his friends, as well as the futility of trying to escape one's past.
One interpretation is that Nick is acknowledging the unrelenting nature of time and how, no matter how hard one tries, they cannot escape their past experiences and the choices they have made. The "boats against the current" symbolize the characters' attempts to move forward and create new lives for themselves, but the "current" represents the past and the memories that continuously pull them back.
Another interpretation is that Nick is emphasizing the theme of the American Dream and how it is an unattainable illusion. The characters in the novel are trying to attain wealth and happiness, but their attempts are constantly thwarted by their past and the reality of their circumstances.
Regardless of the interpretation, the last line of "The Great Gatsby" serves as a melancholic reminder of the limitations of human existence and the inevitability of time's progress. It highlights the futility of trying to escape one's past and the inevitability of having to face and deal with one's mistakes and regrets.