> Copyright law says one thing, but at what point do we as humans say that the creator has died long ago, and his work should now pass to the public to retell as it sees fit?

Especially in this case.

Do you know why Dungeons and Dragons was able to be so Tolkien-esque without being sued? Because there actually was a court case, decades ago, and the only thing the court ruled that the Tolkien people (I don't know if J.R.R. was still alive at the time) actually owned was the word 'hobbit'. Everything else was taken from the public domain. Hence 'halflings' in all subsequent D&D works.

Not that Dune, to pick an example, was that much more original, but with Tolkien's work it's especially easy to pick out the borrowings.