Are there any theories that instead of just being fun, actually add to the story?

One I heard recently: “Given the overt biblical themes and imagery throughout Signs, it’s not a far leap to assume that the aliens are also related to something biblical in nature. As each of the movie’s characters struggles inwardly with their own inner demons, the aliens become an outward manifestation of physical demons. The first clue to this intention is the crop circle, clearly arranged in the shape of a pitchfork. The next is the differing opinions and views of the creatures as the public becomes more aware of them.

Demons are often said to take on the form of their audience’s expectations. Shyamalan posits through this film that in the modern day, most people are conditioned to see demons as a hoax or as otherworldly, non-spiritual creatures like aliens. As such, it’s no coincidence the aliens start appearing around the same time the main character, Graham Hess, admits to losing his faith. Similar to Jacob’s Ladder, Signs draws the protagonist through a Hell of his own creation until he confronts his own demons and finds peace.” -screenrant