Okay, this is going to sound weird, but I've used Keynote in the past. I'm sure PowerPoint can do this as well, but Keynote has Magic Move, and you can export this animation. It's very easy to work with, and do simple animations. I'm sure there are much better tools for this, but as someone who knew Keynote, this was always effective for me.
Keynote is surprisingly good for this, and I’ve used it for animated data flow visualizations in the past.
While I like the idea of something like anime.js and think it raises the ceiling on what’s possible, I’d still probably start with something like keynote just to get the idea out of my head and into a format I can validate before going into code.
