To me, morality is *extremely* important - but to us, not to the universe, the Supreme Deity or whatever. There is no metaphysical dimension to it, it's just the kind of rules we develop around social behaviour in order to live as harmoniously as possible.
The reason why we react so negatively to anti-social behaviour on an instinctual basis is tied to our species's history, linking us to other species that live in social groups (in contrast to eusocial insects and solitary species). As culture-creating entities, we bring significantly more to the table than just hereditary impulses, however, which is why there's more than one morality, and different cultures approach the matter quite differently. Yet at the core of all that, there's a nucleus of well-nigh universal principles, owing to social coexistence.
Morality is also relational and intersubjective: this is why an earthquake is not a moral entity, even if it kills more people than most mass murderers.
Of course, this complicates matters even further. Imagine a superior extraterrestrial species in comparison to whom we looked as primitive and intellectually limited as a farm animal looks to us. Would it be morally wrong for them to treat us like cattle, if we tasted like bacon to them? From our vantage point, absolutely! We'd regard them as the epitome of evil. But what does that say about our dietary habits?
If we suppose that there's an omnimax deity, our actions would be utterly inconsequential to him/her/it. We live on a tiny rock at the edge of a single galaxy in a whole cosmos filled with similar clusters, a microscopic speck of dust. The way I see it, the problem's not so much that non-Christians believe themselves to be perfect, but that Christians believe themselves to be of cosmic significance. There's a whole lot of hubris involved there, if you believe that the entity behind this vast universe is obsessed with, say, what you do in the privacy of your bedroom, or what you put on your sandwich.
Have you ever been morally offended by an amoeba? Do you hold a grudge against a bacterium living on the other side of the globe? Nothing we could think, say, or do could ever affect a divine superbeing. If it chose to pay attention to us, and was concerned for our well-being, it might help us figure out better ways of existing peacefully and happily - but that's not the same as what most religions teach, with angry deities demanding recompensation for personal grievances.
The gods are *too small*, too human. Too obsessed with our species.
All of that suggests to me that we invented them to feel important.