The Silmarillion (down to the basics) are all about the battle between the Valar & Eldar vs. Morgoth w/ crew!
Make this about the breaking of the two lamps and the stealing of the silmarills! Link every story with the help of the silmarills and the on-going wars and BOOM! It's a series
The creation of Arda and the back-story needed to fully understand the conflict could first be told in a very short version in the first episode of the series and then re-told in more and more detail as the intro to each following season!
Much have to be invented/made-up anyway due to the small amount of details and dialogue, so the linking-process should not be that hard if the writers are real fans or the source material