How to change separate strokes lineart into stroke-less shapes?

I made the line art by tracing each line separately, instead of tracing fully closed shapes. Get it? not a separate stroke for each closed shape. Just a bunch strokes on separate layers meeting other strokes on separate layers.

What's the most practical to turn a lineart like this into clean closed shapes? I want to make it a 'strokless' vector without having to redo the whole thing with a different approach.