This is Tolkien, not a nihilistic modern fantasy series. The spiders are evil almost by definition. See the Silmarillion as to the details within the universe.

This is Tolkien, not a nihilistic modern fantasy series. The spiders are evil almost by definition. See the Silmarillion as to the details within the universe. If you have a problem with that, feel free to headcanon it away. I don't care. But in terms of understanding the world of JRR Tolkien at least as written, they're evil. Not just misunderstood, but actively in the service of the outright destruction of the world, lacking only the agency to do so.