I love Tolkien but a lot of his work and themes are riffs on creaky half remembered dark-age mythologies, outside of his core material. The stuff about Numenor is almost painfully derivative. Sometimes though he stops being a philologist and becomes a great writer.
His stuff with Hobbits is one moment - even if they were just off the top of his head and not grounded in any kind of deep mythology, Hobbits as these genial rustic half-sized English civilized country folk is now a timeless invention. My favorite scene in the Silmarillion is one that reminds of a lot of C.S. Lewis. Earendill reaches “heaven” on a mission to appeal to the demigods to save the world, and finds it empty. That was probably the finest moment in the book. Well, and maybe the implication that god bent the world into a sphere from a flat surface to cut off the Havens from the rest of the world. That was an awesome bit of Imagineering.