"Objectivity" is impossible, it is an absolute. Or more precisely, it is a limit which like lightspeed costs more energy the closer you try to get.
Morality is really about understanding the laws of cause and effect within human society. Utility is the only metric of effectiveness and even in this, the subjective utility can obscure the general utility, which may mean that a subjective view from some perspective is accepted though more information would reveal the better utility comes from a broader perspective.
Ultimately all life feeds other life. What may seem wrong from one perspective is necessary in another. Better understanding brings us the ability to make judgements about morality that yield better outcomes for more people.
Murder is said to be immoral, but why is that? What reason supports the concept of private property versus no property?
I say the answer is simply that what is moral has the greatest general benefits to all involved. Utility, results. It takes a long time and struggle as some people benefit from persuading people to adopt morals that in fact destroy, and produce bad results, impoverishing all, this makes it harder for the right prescription to be discovered.
RE: Morality: Only Subjective Or Objective?