Yar, you can do flat art animation in AE and you can use distortion, puppets, expressions, parenting for beautifully stylized character animation. But AE would be where you do your compositing and effects.
Do your character development in an application specifically designed for the task.
I’d examine your goals and work backwards. “2D animation” is a b-i-g realm with more than a century of arts and practices behind it. Your tool of choice will depend on your competence with these arts and techniques. And you must develop your project’s style before you can decide on the tool to use.
If you base your project development by deciding on a tool first, you are constrained by what you know about After Effects before you even start storyboarding.
Keyframe-based tools like AE do not lend themselves to the same kind of personal expression as free-form drawing applications and there is no onion-skinning facility immediately available in AE.
bogiesan
This is my standard sigfile so do not take it personally: “For crying out loud, read the freakin’ manual.”