[conan50]

In the 19th and early 20th century, anthropologists, ethnologists, historians, linguists, and translators did a great deal of work trying to discover and collect myths and folklore, stories from all around the world. It is why we have so many great public domain works of mythology, folktales, and the classics. Along with various translations of Homer's works and Beowulf, for instance, and numerous retellings of myths and folktales. I think both William Morris and J.R.R. Tolkien followed in that tradition, with Tolkien being bold enough to try and create a new mythology influenced by earlier works. The fact he succeeded so well is why we can have this discussion about his influence. But he is hardly the progenitor of it all. He was just very successful.
edit: it is interesting that both Tolkien and Morris tried their hand at translating Beowulf. That story still resonates, and some modern movies make me think of Beowulf and Grendel, the "Alien" franchise for instance..