After a week of trial and error (heavy on the error) I've managed to make a thing. It's not great. I'm no artist and I know next to nothing about animation or digital art. But I made a thing.
It's been a learning experience. I started out in Pencil2D and Synfig and ended up in Adobe Animate (because it has the most recent/coherent/best-for-me tutorials). This was made entirely in Animate with the help of the Gimp (in regards to images I had already drawn but had to trace/redraw). The idea was for the tentacles to move around - this will take more time. There should be several cats. The cat and rabbit should not be singing at the same time. And there should be a song. To which I've timed all of this. It was pretty overly ambitious of me and this is one of my baby steps.