Morality is "real" to the extent that we acknowledge that all humans express (or are capable of expressing) moral intuition. You can't hold the emotion of happiness or the feeling of hunger in your hand, but I would wager that you have strong intuitions about their existence as "real" things.
Utilitarianism isn't the end-all-be-all of moral philosophy. By modern standards, it isn't even particularly popular, compared to hybrid (partially deontological) theories. I think you would also be hard-pressed to find a philosopher who thinks that moral theories can be derived from science alone. Scientific knowledge is often used by philosophers to explain an intuition or support a theory, but few are likely to advocate for cannibalism because we have observed it in other species (and some remote uncontacted groups). That would be an appeal to naturalism or the mere state of things, neither of which is compelling in theories that are meant to explain how we ought to behave.
Thinking about morality as a nonabsolute lands you squarely in the land of relativism. That's a very comfortable place to be, until you meet someone who likes to burn the paws of cats for fun (to borrow Singer's analogy) and have no recourse against their unambiguously immoral behavior.
To wrap up, the goal of moral philosophy is not to "anchor" your preexisting morals and make yourself more comfortable - it is to take (all) moral principles to their logical limits, exploring inconsistencies and gaps that would be unacceptable if applied consistently.
Thanks for the comment. I have to disagree with burning cat paws being unarguably immoral, unless you're talking about a completely fabricated, cognitive, social definition of morality. If you declare, rather arbitrarily, that anything causing pain intentionally for no good reason is in our discussion referred to as "bad" or "immoral," I will agree that burning cat paws is immoral. But that's just a definition we invented; in reality there's no issue with burning cat paws for fun or cutting your fingers off when they get dirty or shooting rockets at the tailgater behind your car. Yeah there's going to be pain involved, but there's nothing fundamentally wrong with pain at all.
Consider the following: What type of world would ours be if everybody tortured cats for fun? Intuitively speaking, would that be a "good" world, or at least one that is more "moral" than our current one?
Morality itself may not be universal in the same way that protons and neutrons are - it's unlikely that CERN will ever find a fundamental particle that interacts with humans to produce moral behavior. That being said, it isn't necessarily impossible to conceive of a (universal, consistent, intuitive) code whose rules maximize some moral good[1] (whether that good is pleasure, longevity, number of M&Ms per capita, etc).
We can argue back and forth about whether moral goods are social or universal (I personally think that it depends on the moral good being considered), but neither option seems to detract from the core calculus of moral philosophy - whether or not someone ought to do something. If that fundamental question resonates with you, then you've just made a moral consideration. The trick then is to understand why you've made that consideration, whether or not it is a consistent one, and what first principles inspire it. If you think that question doesn't resonate with you, you might be an amoralist[2].
[1]: I apologize for re-using "good" here - I'm using it in the sense of resources, not the moral sense. In the context of (utilitarian) moral philosophy, moral goods are those resources that we ought to maximize.
[2]: Bernard Williams has written very extensively on amoralism, and particularly on the inconsistencies that amoralists must concede upon being presented with their own behavior. Ethics and the Limits of Philosophy and Morality: An Introduction to Ethics both contain great passages/chapters on amoralism and its inviability as a philosophical model.
Utilitarianism isn't the end-all-be-all of moral philosophy. By modern standards, it isn't even particularly popular, compared to hybrid (partially deontological) theories. I think you would also be hard-pressed to find a philosopher who thinks that moral theories can be derived from science alone. Scientific knowledge is often used by philosophers to explain an intuition or support a theory, but few are likely to advocate for cannibalism because we have observed it in other species (and some remote uncontacted groups). That would be an appeal to naturalism or the mere state of things, neither of which is compelling in theories that are meant to explain how we ought to behave.
Thinking about morality as a nonabsolute lands you squarely in the land of relativism. That's a very comfortable place to be, until you meet someone who likes to burn the paws of cats for fun (to borrow Singer's analogy) and have no recourse against their unambiguously immoral behavior.
To wrap up, the goal of moral philosophy is not to "anchor" your preexisting morals and make yourself more comfortable - it is to take (all) moral principles to their logical limits, exploring inconsistencies and gaps that would be unacceptable if applied consistently.