What?! Ancestor of English... Ok so first of all modern day "England" pretty much all "Germans" if I'm not mistaken... due to repeated Viking and Saxon invasions over the course of like 1000 years until like all the "Bretons/Dunmonii" whatever were dead.
Or exiled to Wales and Brittany, yep, although IIRC the genetics data says that they were culturally absorbed rather than outright exterminated. However, the Vikings brought plenty of language elements over, and then the Normans brought French. The fundamental structure of English is a debased version of German, but the vocabulary's a mutt.
Plus Elvish isn't a real language, that's like saying well you need to have this translated name to understand my imaginary name again. Well, we don't really need your imaginary world though, I mean, hopefully it is interesting, but this is a case of historical materials being essentially the same as the "imaginary" ones.
Well unless you value Quenya merely for the fact that it's an invented language but I don't really care for that aspect.
Yep, he made up Elvish. And yeah, we don't need either. But his concept was that you couldn't have the language without the history and mythology, so making up the language required him to make up the rest too.
As for whether you or I or anyone else cares about that, well, he did not do this for our approval.
Here's an interesting document. Note that Tolkien was being easy on the translators here WRT the word "hobbit;" technically a translator could have been expected to have to make up a new word the way Tolkien himself made up hobbit from Old English elements.
I think actually my point is that LOTR is like a more extreme Viking version of traditional norse mythology,
This doesn't strike me as being a particularly useful way to think about the work. At the level of generality we'd need to use to make that stick, I could map it onto just about any religious tradition.