Contains spoilers for the full Haruhi series, season, season 2 and the movie. Though I guess if you are browsing a Haruhi community in the year 2023, you have seen it all already.
Spoilers begin below:
Haruhi has godlike powers and manifests her wishes into reality
Or does she?
I forget which LN it was in. Tanigawa briefly teased the concept that Haruhi wasn't the one with godlike powers, but it was actually Kyon. It wasn't a big tease. It was mentioned in an offhanded way in part of a paragraph and then never brought up again. However, it was a thought I had had before reading that, and seeing that Tanigawa even thought of it too (although maybe he only considered it as a throwaway line) sort of makes me feel like there is some substance there.
My understanding of this theory is that Kyon's desires manifest everything in the world, though because he is in such heavy denial that aliens, espers and time travelers exist, he can only envisage this sort of thing happening if someone else is manifesting it, that someone else of course being Ms Suzumiya.
As a semi-related side note: have any of you read the Michael Crichton novel The Sphere? Or seen the late 90s movie based on it? The idea of people wielding Haruhi-esque godlike powers and manifesting subconscious desires into reality is a major part of the plot in that story. Crichton (at least in the book version) also does a good job of writing about the psychology of how and why such a thing could happen. Actually, the first time I watched Haruhi and Koizumi explained her godlike powers, my thoughts immediately went to this book first.
I always figured it was pretty much canon that Kyon is what he was told Haruhi was given how many different things in the series hint that that is the case.