Without commenting on whether this presentation matches the original metaethics sequence (with which I disagree), this summary argument seems both unsupported and unfalsifiable.
Would this be an accurate summary of what you think is the meta-ethics sequence? I feel that you captured the important bits but I also feel that we disagree on some aspects:
V(Elves, ) = Christmas spirity
V(Pebblesorters, ) = primality
V(Humans, _ ) = morality
If V(Humans, Alice) =/= V(Humans, ) that doesn't make morality subjective, it is rather i...
Unpacking "should" as " morally obligated to" is potentially helpful, so inasmuch as you can give separate accounts of "moral" and "obligatory".
The elves are not moral. Not just because I, and humans like me happen to disagree with them, no, certainly not. The elves aren’t even trying to be moral. They don’t even claim to be moral. They don’t care about morality. They care about “The Christmas Spirit,” which is about eggnog and stuff
That doesn't generalise to the point that non humans have no morality. You have m...
Morality binds and blinds. People derive moral claims from emotional and intuitive notions. It can feel good and moral to do amoral things. Objective morality has to be tied to evidence what really is human wellbeing; not to moral intuitions that are adaptions to the benefit of ones ingroup; or post hoc thought experiments about knowledge.
Also, I did not say that people would be wrong if they started calling all cats and dogs "dogs." I said that this would not mean that there were not objective differences between the things that used to be called dogs, and the things that used to be called cats. In fact, the only reason we are able to call some dogs and some cats is that there are objective differences that allow us to distinguish them.
Not all semantics is based on objective differences. There's no objective feature that makes someone a senator, or a particular piece of paper money..we just have social conventions, coupled with memorising the members of the set "money" or "senator". So if you arguing that "good" must have objective characteristics because all menaingful words must denote something objective, that doesn't work. But it is not clear you are arguing that way.