That was Tolkien. Well, I think it's from the posthumous compilations of his notes by his Son, so maybe isn't Canon.
People act like Tolkien is sacred though, so I'd bet its Canon now whether he intended it or not.
And, I agree, Norse Mythology is awesome. It's incredible how much cool ideas from the stories we all love are just lifted right out of it.
Agreed on Norse mythology being awesome and way more than Thor, Odin, Freya, Loki.
However, northern and northwestern European mythologies have so many overlaps in names of creatures and how they behave, close enough to be considered the same but different enough to make one stumble. Most notable in Elves, but also Trolls and different other well known terms (and variations) were travelling the mythical lands everywhere. One of the celtic elf variations actually is pretty much what dwarfs are, akin to the black dwarf question posted above, living underground, no magic but technology, and so on. So it probably is hard to say "this is the one way to do it" and Tolkien just did what he liked best as did many other authors (think of Pratchett's Elves as an example, although they maybe shouldn't count since they are an intentional counterpoint to Tolkien). We might prefer a different variation.
Personally I like the "androgynous" approach, where I mean men and women are hard to distinguish for outsiders, because it is something different than just "humans who are smaller/taller and have certain preferences". For the purpose of games on this site however, it is difficult to do it that way. But in terms of fantasy, a dwarf ain't just a short human, nor is an elf just a longer human with magic.