Hopefully this question makes sense and I'm not an idiot.

I had a shed built, corner posts sunk in concrete, structure of the shed probably about 6-12" off the ground (required two steps for entry). The base frame is 2x10s I believe, with exterior plywood on top making the floor. The siding is 2x4s with exterior plywood, then tyvek, then hardie board. I can try and measure the exact plywood thickness, and verify the 2x4s/2x10s if needed.

My question is I'm wanting to put some sort of flooring on top, just to keep it a bit sealed, and so any spilled whatever doesn't damage the only flooring. I'm going between the rubber tiles used in gyms or some similar garage tiling, or just another layer of (non exterior?) plywood that I can paint with something wipeable. Should I put tyvek down between the layers, or would that allow moisture to build up on the floor frame/floor plywood?

Thanks!