Elves are elves! Tolkien was working very much with the recieved
traditions in ballads and so (which he altered quite a lot, but still)
The only reason Sindarin looks vaguely Welsh is because Tolkien thought it
sounded nice (which it does); Quenya, on the otherhand, has got elements of
Finnish in it, though it's nothig like as hard. I seriously doubt that
Tolkien was uncritical enough to believe any race of humans would be benign
nature lovers - he was, for instance, well aware of the nasty side of pagan
Germanic culture, however moving the poetry which descended from it (the
Vikings and their blood-eagle ritual, for instance).
If there is a "Celtic" people in Tolkien, it's probably the men of Gondor, who
have definite Romano-British elements. They certainly aren't Old English
- unlike the Rohirim, who, as is frequently pointed out, are West Mercian with
just a touch of
Goth....
