Shape layers are completely different tools than you find in Illustrator. The only comparison is that you have a vector path that can have a fill or a stroke.
If you want to bring a complex Illustrator file into After Effects and manipulate everything on layers, create your AI file, open or start a new AE project, open Adobe XD, choose File/Import in XD, and choose your Illustrator file as soon as it opens select File/Export/After Effects and a new AE project and comp will be created with every AI asset available for editing as a shape layer, brushes and gradients included.
Be prepared. You are going to end up with a layer for every element in the AI file.
I appreciate your lengthy reply and I do know how to do that. That's not my point. I should be able to pick up a paintbrush in after effects and swirl it around. It doesn't have to be Victor but it has to be there. One of the many reasons I'm switching over to blackmagic Resolve… In fusion I can grab a paintbrush and do whatever needs to be done. For pure graphics, nothing can compete with after effects… But as an editor, resolve blows premiere Pro out of the water in every possible way. And although I will never give up after affects… I'm doing a lot of basic stuff in fusion.
You're asking to replicate a toolset that itself has evolved over decades in AI and consists of a subset of methods that are hugely different. I can see no realistic way to implement that in AE and the same goes for Photoshop brushes. Could AE use better brush tools? Sure. But just transpalnting another brush engine is not the answer, given that they all have their own quiks and caveats.
I understand what you're saying and I agree with you. But then at least give us a great set of after effects brushes just simple paint brushes and again they don't have to be vector they have to be good. And plentiful. And then give me a way to distort the brushes and twist them and turn them and even make them "drip-able"!