Copyright of individual stories and characters expires at the earliest time, not latest. So Sherlock Holmes the character hit the public domain before all of the Sherlock Holmes stories did.
Tolkien’s work will start bubbling into the public domain as soon as 2031. Considering he wrote the material to form cultural legends for the English speakers of the world, that sounds like a good thing. Considering how bad some adaptions are, that sounds like a bad thing.