He is no exception in terms of his ignorance. We're all ignorant to one degree or another, but people 2000 years ago were significantly more ignorant - particularly, I would say, when it comes to knowledge of the human condition. The bible is a collection of beliefs - of knowledge from the time, and thus reflect the time - and state of knowledge at the time - of their writing. And in many ways the shortcomings of that knowledge are only too apparent.
His writing is steeped in the cultural context of the times. He writes from his understanding of things, and writes for audiences (and their attitudes) that he was seeking to convert to his fledgling religion.
If I could transport a man from 2000 years ago and sit him next to a modern psychologist, who would you be more inclined to listen to on matters of the nature of being human? If I told you the man from 2000 years ago was divinely inspired, would you believe me, and then thus, him? If you believe Paul because you believe he was speaking from the Holy Spirit or whatever, there's nothing I can say to you to make you accept the above. But I do not believe he was so inspired, and I think it's fairly plainly obvious that he can be placed 'in-context', that he was a man of his times with specific goals in mind, and that his writings were of their time, just as with any writings in the Bible. And because of that, to modern eyes, such writings are often cringe-inducing in their ignorance (I needn't go through the list...read Leviticus, and its sage wisdom on female hygiene and purity for one nice example if you must).