Let's at least be honest about our moral/ethical frameworks. They are useful for social cohesiveness, peace and order. But they're still just made up.
I don't have time for a complete response, but as an expert in this field (ethics) I feel compelled to let you know that nearly every professional philosopher (particularly in ethics) disagrees with this position.
Ethics is not simply whatever the majority says it is. You're not going to get anyone in ethics (including those who think ethics are in some sense "made up") to sign off on that.
So you are (at least partially) defining ethics by the consensus of people (in your case professional philosophers).
Even in pure mathematics, which is considered to be among the most rigorous of fields, a whole lot depends on consensus about axioms and consensus about what is a valid proof.
Yes, I agree there are logical principles for determining ethical actions given a set of ethical axioms, but however, the ethical axioms themselves, and indeed the logical principles, are determined by consensus.
I am not. I'm saying that people on HN make some very hasty assumptions about ethics (e.g. the claim made in the parent comment) that ethicists broadly agree are deeply misguided. I'm hoping to encourage a little more caution. Ethics are not defined by what professional philosophers agree on, but professional philosophers are in a good position to point out when lay comments are making simple mistakes in their reasoning. This is such a case.
My personal belief is that we have a responsibility for all species on our planet (as the most intelligent, evolved, smart, etc of them). Even if everyone believes except 1 person that does not make their argument less or our argument more valid. Purely from an ethical perspective.