Like you - I thought he might be gifted but not highly or profoundly gifted. He asks/says those interesting things ("Time is the most powerful thing of all because if time didn't exist, nothing would exist."). He loves to learn new things, and he does learn them quickly. E.g., once he DID learn to read, he went from K level to reading just about anything in a matter of weeks.
But he didn't read early, didn't/doesn't do accelerated math, etc. He doesn't demand extra academic work, isn't a musical prodigy, hasn't built anything breathtaking or written intricate stories or any of the amazing things you see kids on these boards doing. Nothing. At. All. Just those flashes of something I can't quite describe.
Again... you could have written this about my DS7.
I know those flashes well. He gets on these streaks of inspiration and you're just along for the ride. He recently explained to me that, when you draw a triangle, you're actually drawing an infinite number of triangles at once because the line that you draw the triangle with has a thickness which can be divided infinitely. One of my other favorites was when he was on a philosophical tear. It ended with, "Dad! We [our existence] are nature's art!"