Where did the rank of commodore come from?

Is commodore a Dutch rank in origin?

No. It is traced to the French commanderie and entered naval use as a temporary squadron command title.

Commodore is traced to the French commanderie, a title associated with a knight responsible for part of an order's territorial holdings. The Dutch adapted it for naval command, often as a temporary appointment rather than a permanent rank. The Royal Navy then used the title for a captain placed over a squadron of several vessels. This delegated senior command without the expense and permanence of creating another admiral, making commodore a practical answer to fleet organization rather than a uniquely Dutch invention.