"His legendarium and the characters therein" includes Balrogs (ancient demons), angels in human form ("Wizards"), Mighty elf lords, flawed but determined men, ax wielding dwarves, and a story that is deeply spiritual.
And yes, there are hobbits in there too.
For me it was the reverse. Tolkien was my first contact with art and culture. My mother read it to me before I could read myself. I listened to the radio dramas when I was growing up in a house without television. Batman came much later in my life.
Regardless, I hold this truth to be self-evident: There are a few messages in Batman that are emotionally resonant and a couple that I might go far as to say "spiritually" resonant, but the superior depth of Tolkien's world and message is undeniable.
That is all.