I thought a fictional universe doesn't have the same human races as Earth, and also might be contrary to Tolkien's vie since Earth doesn't have hobbits, dwarves, elves, and orcs.
https://en.wikipedia.org/wiki/Red_Book_of_Westmarch
That backwater agrarian villages/hunter gathering tribes have the same diverse ethnicites as downtown Los Angeles is a different issue.
Mediterranean
middle earth is a borrowed concept
As a scholar of early medieval literature, Tolkien borrows tons of ideas from the Edda and other mythological sources. (To give him his due, he masterfully reinterprets and combines what he „borrows“.)