Differentiation is not the same as discrimination. The protected categories exist because harm was done on the basis of these identifiable traits.
If all humanbeings were ethical and always did the right thing (which matched the universally shared definition of the right thing), we wouldn't need these laws. Since neither the universally accepted definition or the universally ethical people exist, we are stuck with the flawed legal system. Doesn't mean we shouldn't try to make it better though.
That's the point I was trying to make - it doesn't exist and laws at best convey the ethic that the majority does not care to oppose at the time of enactment.
I'm interpreting (the first part of) your post as "humans cant do the right thing so we need laws to force them to do it".
I know the right thing for me. I don't need laws telling me about the right thing for me. No other human, or law, can know the right thing for me. And I humbly accept that neither can I know what's the right thing for others, nor construct laws that could guide any other person to the right thing for them.
"I don't need that law telling me the right thing for me" probably wouldn't go over that well in court but if you want to try it then go for it.
The nice thing about laws is that they aren't asking for your permission. They aren't a suggestion, they are telling you things you can't do. If you don't like them you are free to attempt to change the laws but until you do that it's literally "obey or else."
That's not where I was going with this and I'll respectfully disagree with your statement because in a society, there has to be a balance between conflicting interests. If what is good for me will cause harm to you, societies generally will want to limit the extent of the harm, so that some socially acceptable balance exists. It's not always all that well balanced or well implemented, but it tends to be adequate on very catastrophic things.
But again, all human systems are flawed in different ways and it's extremely important to recognize those limitation and consequences, and not just let systems grind people up.
If all humanbeings were ethical and always did the right thing (which matched the universally shared definition of the right thing), we wouldn't need these laws. Since neither the universally accepted definition or the universally ethical people exist, we are stuck with the flawed legal system. Doesn't mean we shouldn't try to make it better though.