Thanks for playing! I agree with your critique, in hindsight I think the only times you would ask "what does this button do" is right after collecting the rune; then you know, so there's not much more to it than that. Maybe an interesting spin could've been having separate levels where the rune maps to a completely different action in each level (i.e. the left rune now makes you jump in another level), so you have to keep guessing.
Great point about the GMTK game jam correlation, I didn't think about it at the time but this game definitely borrows that idea about controls being part of the game world. I thought that was a cool application of the theme in that game jam, so I'd love to explore this idea more when I get the chance!