Very definitely D&D has sword & sorcery roots. The magic system comes from the works of Jack Vance (and I always kinda disliked it. I'm glad we've somewhat moved away from it).
JRRT may never have believed in inherent evil, but the orcs were explicitly evil. We *never* see a renegade orc. And when you combine this with the alignment system, you get a problem.
Your fanfiction sounds fascinating, but understand that Rowling's goblins ARE an anti-Semitic stereotype. Unfortunately, it's a very common one, to the point where a lot of people use that stereotype (the Race Of Bankers Who Control All The Money For Mysterious Reasons) without realizing what it is. Alastair Reynolds does it in the otherwise fantastic Revenger books too. It gets to the point where we get tired of educating people.
Melkor is really just another name for Lucifer.