Meh, I'd be far more interested in The Silmarillion brought to screen rather than a narrative arc.
I think about this more than I should. I'd love it but there would be scale and narrative arc issues... Basically LotR was three movies featuring three primary set pieces, Moria, Helm's Deep, and Pelennor Fields, but Frodo's arc ties them all together.
Recon you could leave out the Ainulindalë, the Valaquenta mostly and all of the Akallabêth, but you just don't get that Frodo-like continuity throughout the Quenta Silmarillion. There are only two characters there from the get-go to the end nearly 5000 years later... Morgoth, but he's the antagonist and the story really is all about the protagonists, and Galadriel who spends most of the First age in Doriath and takes no real part in the events of the age, and therein lies the problem.
Do you follow Fëanor for the Silmarils and oath, sure, but, you know, Gothmog ends his arc.
Fingolfin? Nope, 'cos Morgoth ends his.
Fingolfin's descendants? Fingon? Nope, Gothmog again... Turgon? Better option. Gondolin 'tho... Turgon gets you Idril and Tuor 'tho, and that gets you Eärendil. Eärendil gets you Elwing (also Elrond who could also connect dots for movie-only folk) who connects you to Thingol and Melian (with Galadriel as the bit player) but arguably opens up the best arc of the whole Quenta Silmarillion, Beren and Luthien.
So, no one to really anchor the whole story for folks watching a movie/movies.
Also which set pieces and arcs could you leave out to manage run-time? Morgoth and Ungoliant? Fëanor killing Elves, burning ships and fighting Balrogs? Sudden Flame and Fingolfin fighting Morgoth? Unnumbered Tears? Beren and Luthien? Túrin? Gondolin? Eärendil's voyage? The War of Wrath?
As I said, scale and narrative arc.
Anyway... Back on topic, I suspect Jamie Dornan will do just fine as a younger Aragorn.