It is worth pointing out that Tolkien was a phonologist--a linguist specializing in how words sounded--and his stated goal for the entire Middle-Earth universe was to provide a mythic backstory for England.
These two facts converge to make claims of originality very strange and difficult, because the derivations themselves are examples of original work.
I've been reading a book on Irish Mythology (Lady Gregory's compilation) and it reads a lot like LoTR
Tolkien came up with new stories and characters, but the style is similar (and of course with sources from Norse Mythology and others, that mixed and grew apart, etc)
I very much recommend Tom Shippey's Road to Middle-Earth, which discusses Tolkien's influences from the perspective of a contemporary and friend and academic colleague.
No. He was a philologist. Whatever… I agree with the rest of your comment.
For more background, Tolkien was heavily inspired by - among other material - a compilation of Finnish oral tradition called "Kalevala". I've read that he used to complain that the English culture lacked such a tradition which most certainly lead to what the Silmarillion, The Hobbit, The Lord of the rings and everything else.
These two facts converge to make claims of originality very strange and difficult, because the derivations themselves are examples of original work.