The gameplay was familiar, but comfortable. I couldn't help but smile repeatedly throughout, partly because of the cute aesthetic and partly because of the simple but enjoyable gameplay. It's nothing revolutionary, but it's very easy to get into and to just keep going and going with. It feels like a comfy minigame that's just a tad above being an idle game.
It looks very cute, and I'd like to see the symbols and the main character used again in games. The audio fit the game very well; there could have been more variety in the sound effects (just as there could have been more variety introduced as you go in the falling icons), but something about that music was just infectious, in the best way.
The theme was used well, since, as you said, all the falling things are light-related; the sound effects also made "light" come to mind, and the contrast with the night skyline background made the light elements feel more significant. Good job with that.
The "Only One" limitation wasn't really followed in any noticeable way here; I think a lot of people miss that.
It was just cute and fun, and I did feel like I could play it for a long time without stopping, so it definitely has potential!