I see nothing being animated because my system is set to prefer reduced motion. That's a cool accommodation, but I wish at least the demo page made that more obvious.
I see you added a button (thanks!), but that doesn't solve the information problem where the person won't know why it isn't working and that they need to click the button. I suggest a simple highlighted message right above or below the image. Your "holds the first frame for anyone who prefers reduced motion" blurb is _buried_, and in my case I didn't even know that I had that enabled.
Also, the art scenes section is not ASCII.