i cant walk through the humanrootpart even if cancollide unchecked why?

I made a pet for my game and the pet has animations I want to make the pet Noncollision so it can go through the player if it got too close to him so I turned off CanCollide for all parts in my pet then I ran the game to test it and I actually been able to walk through all the parts except the HumanoidRootPart and the CanCollide was turned off! , I can't understand why! can anyone explain to me why?

You cant turn the collision off on some parts by altering their properties. I would look into collision groups.