[nirava]

Anyone know of good alternatives to this?

I’ve used Adobe Flash since it was still Macromedia Flash, and this is the software my brain kind of defaults to when thinking of creating little graphics and animations. Just as hobby for random tiny projects.

But what do people use that is not Animate for really quick animations and mock ups?

[JBits]

Clip Studio Paint seems very popular for animation. You could also consider Aseprite for pixel art animation.

[avtar]

While not a one-to-one situation, probably Blender and specifically Grease Pencil?