In Pirates of the Caribbean: The Curse of the Black Pearl, Jack Sparrow bribes the dockmaster to keep his name off the books, and the dockmaster greets him as "Mr. Smith". Is this an anachronism (the film ostensibly takes place in the early 1700s), or has the name been that common throughout English-speaking history, similar to John Doe?
This has to be answered somewhere on our subreddit already, I would be surprised if it wasn't. Did you check the r/AskHistorians FAQ for this (as in the one that lists frequently asked history questions)?
I can tell you that John was pretty well common enough name by the Golden Age of Piracy (as for Pirates of the Caribbean the film, that is pretty well set in it's own universe that is outside being on an actual year) of 1690-1725. The Sailor's Register of 1693 (that failed to get more than 5,000 names when there were closer to 50,000 mariners in England) had literally one of every five sailors listed with the first name as John.