You can use Motion to animate. There are animation apps that can "flex" artwork to animate human figures, but just about anything they can do can be accomplished in Motion. I would recommend a drawing app to create your characters though. Motion does not have a "paint" function — most of it's artwork stuff is vector.
I recommend drawing parts: head, trunk, arms, legs, feet, with however many sections each requires. I recommend drawing view variations like "full frontal", side view, "three-quarter", etc.
Building "switch layers" is not that difficult (moving lips, blinking eyes, etc.). Using Anchor points will help you create "joints" at which rotational animation will occur. Careful grouping of layers will help assemble bodies that work easily.
I did this about 8 years ago:
https://youtu.be/39RudFFJ5FI
There's a link in the description to download the Motion project I used. The project uses Oscillate behaviors for all the character limb animations and a Throw behavior to move it across the screen. Normally, you would NOT do this!!! There are plenty of resources out there that are better guides to animating cartoon characters and each "cycle" would be better keyframed!
The project just uses basic shapes drawn in Motion (he looks like a jogging peanut!) because I was only making a specific point back then. Here's my original post (it may have a bit more information about the project file)
https://discussions.apple.com/thread/4534204?answerId=20383393022#20383393022
