If there are objective facts “floating out there” about math, biology, etcetera, why can’t there be objective facts about morality?
Because the objectivity of statements about math, biology, etc. can be verified by posing a scientific question. In other words, something like 1+1=2 is a testable claim. We have seen no occurrence of 1+1=2. Hence, we can say that “1+1=2” is a law of nature. “Moral truths” are simply not testable.
If the answer is that it is difficult to know what the moral facts are: some facts are more difficult to find out than others. Physics didn’t know about the Higgs Boson for centuries and yet here we are. Perhaps philosophy could do the same thing with moral truths in time
And the Higgs Boson became an “objective statement” only after it was verified. Prior to that, it was just a hypothesis. Do you have any scientific evidence to suggest that there are certain universal moral truths that apply to all humans?