It officially introduces the concept of the Klabautermann into the One Piece mythos.
"The Man Who Is Loved Even by His Ship! Usopp's Tears!" One Piece (Dub) Episode 247
Compare the here to how it's referenced later in the series. Let me know how you'd like to dive deeper ! Episode 247 | One Piece Wiki | Fandom It officially introduces the concept of the Klabautermann