[swannodette]

Some scholars believe it to be an early work - possibly Bach was 19 years old. No copy in Bach's hand has ever been discovered, so there's no certainty. It is a wonderful, memorable piece of music but Bach was pretty good at that and not just at the keyboard.

[tgv]

Some believe(d) it to be written by someone else! No candidate was found, though. It's definitely an earlier work. It's much more in the style of (e.g.) Buxtehude than Bach's later works. If you like BWV 565, the Toccata and Fugue, you could check out e.g. BuxWv (a numbering like BWV) 149 and 156.