Whether Tolkien is overrated or not, is beside the point, he made up orcs more or less from scratch, and his elves had bugger all to do with European mythology elfs. At most you could say he stole the names but that's pretty much meaningless. Fantasy in the modern, literary, "elves and epicness" sense of the word is derived from Tolkien.
Also, I'd like to point that while Tolkien wasn't, in any way a great writer, modern fantasy writers haven't exactly improved upon him.