"it just feels to me like the bible was written by men & not by god..."
Right. When you start to understand the cultural, social and political setting, ie, what was going on in the ANE at the time, it becomes a little easier to understand. Why the big laws on fornication and adultery? Having children was the most important thing anyone could do, and for a man, having plenty of sons to protect the settlement, carry on the name and leave the farm to was critical. Tight control on women meant tight control on fertility--you wanted to know that the baby she was carrying was YOURS and no one else's. You might have noted that that the laws re virginity were only imposed on women, not men.
Actually, there is no law against fornication per se in the Mosaic Law Code (please, correct me if I'm wrong). There are laws against sleeping with a virgin (damaging someone else's goods, as Nark brought out) and sleeping with someone else's wife (stealing someone else's goods) but there's no explicit prohibition against, for instance, a widow without family sleeping with an unmarried guy she's not related to, as long as she's not in her father's house (b/c she's once more her father's property and good for re-sale). Each of the laws restricting sex have to do with either woman's value as property, incest or controlling who the father of offspring is (adultery).