The rampant dismissal of so many restatements of your position has tempted me to try my own. Tell me if I've got it right or not:

There is a topic, which covers such subtopics as those listed here, which is the only thing in fact referred to by the English word "morality" and associated terms like "should" and "right". It is an error to refer to other things, like eating babies, as "moral" in the same way it would be an error to refer to black-and-white Asian-native ursine creatures as "lobsters": people who do it simply aren't talking about morality. Once the subject matter of morality is properly nailed down, and all other facts are known, there's no room for disagreement about morality, what ought to be done, what actions are wrong, etc. any more than there is about the bachelorhood of unmarried men. However, it happens that the vast majority kinds of possible minds don't give a crap about morality, and while they might agree with us about what they should do, they wouldn't find that motivating. Humans, as a matter of a rather lucky causal history, do care about morality, in much the same way that pebblesorters care about primes - it's just one of the things we're built to find worth thinking about and working towards. By a similar token, we are responsive to arguments about features of situations that give them moral character of one sort or another.