How much of D&D was "borrowed" from J.R.R. Tolkien?

How much of D&D was "borrowed" from J.R.R. Tolkien? 

For what was supposedly an original idea when it first came out, Dungeons &
Dragons (D&D) heavily depended on other sources for its material. Most notably,
D&D's co-creators Dave Arneson & Gary Gygax made heavy use of the works of J.R.R. Tolkien.

For instance, the "Halflings" were the Hobbits from Tolkien's work. Actually, the word Hobbit was 
originally used in D&D until the estate of J.R.R. Tolkien demanded that they cease and desist. Additionally, 
the varieties of elves in D&D has a distinct resemblance to the elf races in Tolkien's works.

For all practical purposes, D&D was an outgrowth of Tolkien's fantasy works. 

What all this goes to show is that D&D just simply was not all that original. Or at least not as original
as advertised.