I'm not sure how you got to the topic of mutability. I never mentioned that.
You're wrong about mathematics, though. Man did not create the laws of mathematics, we discover them. They would be true if nobody ever thought about them.
Thus, they are transcendent. The same applies to morality. If its truth exists independently of our thoughts about it, it's transcendent. If not, then moral right isn't really "right."
Light and eyes are physical things. Math and morality are not.
Colors are dependent on our experience of them. They are not transcendent like math and morality (assuming the laws of math and morality exist at all). However, our experience of colors is caused by something outside of us. Similarly, you could say that our systems of describing morality and math are dependent on our own minds. But the truths that we are attempting to articulate are not.
I never said anything about taking morality out of a human context. I agree we can't do that. However, if no human anywhere acknowledged any moral laws, those laws would still exist, and be broken whenever people broke them. If this is not the case, then something thought to be morally right isn't really right. It's a fiction. The definition of morality demands that, for it to actually exist, it must be transcendent.