If I were going to ask Professor Tolkien a question it would be why should LOTR be a mythology for England instead of a great addition to a very rich although sadly at times fragmented tradition?
At the time these poems were sung, nations had not yet emerged and folk lived in a tribal society. Beowulf in todays terms would've been a Swede, but he would've feircely referred to himself as a Geat. The pre migration folk of southern Jutland could be called Danes but they would've refused the label preferring to be called Angles.
As our ancestors moved they took their tribal affiliations/Indentities with them, as the Angles Kingdoms sprawled across most of Great Britains land mass, Anglelond, got its name. But along with Angles, came Saxons, Frisians, and Jutes, incidentally Jutes could also be considered Danes by todays standard. Later predominantly Danish and Norwegian Vikings raided and settled as well.
Svein Forkbeard conquered most of England and his son Cnut dealt the death blow to the Saxons at the battle of Ashingdon in 1016 and was crowned King. Incidentally in the revolts against William in the 1070's Anglo-Danish earls in the North enlisted Danish aid.
My own ancestors were Danish in origin the three earliest are named Arnkell, Dolfin, and Thorfinn, decidely Scandinavian names despite the last two being englishmen by birth,they were born in Dentdale, "Granpappy" Arnkell was the only true Dane we could trace. Yet despite the change of location the names, presumably culture and language remained almost purely Scandinavian for two generations
My point in all this is that taken together England already had a massive amount of heroic literature, that was richly diverse, from a tribal perspective.
I am looking forward to your thoughts and to a thought provoking discussion
