I think it's fairer to say that none of us do, by nature or instinct.
One of the remarkable things about the Bible is this: it's easy enough to understand that even a child can grasp its core message, and complicated enough to have legitimately occupied the world's leading literary, philosophical and theological scholars over millennia.In addition, although to the Christian morality may be objectively determined by God, God's will is not always objectively apparent. The Bible is a complicated and difficult book, subject to many interpretations.
On the surface, not hard; in application, more demanding, but still doable.Even seemingly direct commandments (like the ten) are subject to interpretation. Kill? Murder? Is first degree manslaughter prohibited?
What you'll find is that the majority of cases are actually not very hard. It's the liminal cases, the one in which values are set off against each other that require precise discernment. And we all have enough of both, in life.
If we attend to the unproblematic cases, we will acquire skills at discerning more difficult ones. And God Himself has promised to supplement the wisdom of those who lack it, if they ask in faith (Jas. 1:5-8).