"A story doesn't need a theme in order to be good" I'm only saying this once but a theme isn't some secret coded message an author weaves into a piece so that your English teacher can talk about Death or Family. A theme is a summary of an idea in the work. If the story is "Susan went grocery shopping and saw a weird bird" then it might have themes like 'birds don't belong in grocery stores' or 'nature is interesting and worth paying attention to' or 'small things can be worth hearing about.' Those could be the themes of the work. It doesn't matter if the author intended them or not, because reading is collaborative and the text gets its meaning from the reader (this is what "death of the author" means).
Every work has themes in it, and not just the ones your teachers made you read in high school. Stories that are bad or clearly not intended to have deep messages still have themes. It is inherent in being a story. All stories have themes, even if those themes are shallow, because stories are sentences connected together for the purpose of expressing ideas, and ideas are all that themes are.
Thinking about how Elrond is always a supporting character.
Back during the first age, when the sun was still new and I read the Hobbit and Lord of the Rings for the first time, one of the things I remember thinking is that there is all this lore about Elrond specifically and Imladris more generally that are referred to in passing as the major players in the story interact with the it. And then the story moves on because it’s not about Elrond.
And the thing is, the story is never about Elrond. In the Second Age he’s overshadowed by Gil-Galad and Celebrimbor and by the mortals in the story, like Elendil. Like, even in the story about his birth and upbringing and stuff, the focus is on Elwing and Earendil and Maglor and Maedhros. Hell, even Elros gets more of a character arc than Elrond.
And actually, the more I think about it, the more it makes perfect sense. Because Elrond is the goddamn universal constant. If you’ve ever interacted with any Tolkien based media, you know who Elrond. Galadriel is older but she doesn’t appear in the Hobbit, and Gandalf is a full age from being sent to middle earth even at the end of the Silmarillion. Elrond is everywhere. When Elrond appears, everyone is like ‘oh, it’s Elrond, I know what his deal is.’ And that applies to both readers and characters.