That's one view. But religious people would say they are divine constructs that are ascertainable by humans, and that left to their own devices humans would not develop them. Even as you look at developing moral systems and values over time, one can credit the hand of god for guiding humanity if one is so inclined. I've heard often, from religious people, the idea that without god there can be no morality.
Yeah, this is actually a debate for an entirely other issue (probably a different forum, actually). I think the idea that "without God there can be no morality" is a load of garbage. Whether or not you believe in God, if you think people who don't accept God aren't capable of morality, your head is up your anus. Morality is definitely a human construct, and therefore what is and isn't moral is all a matter of perspective. Look at marriage as a perfect example. In the middle ages (and long before it), as soon as a girl could menstruate (usually around age 13-14), she was fit for marriage and having babies, usually with an older man. Now, these girls would be considered minors, and a man over age 18 having sex with a 14 year old girl would go to jail.
This wasn't even a moral decision in their eyes, that far in the past. It was a practical and economic way of life. Now that other factors have changed (like women's rights, less need for child labor, etc.), morality has changed with it. Again, its all about perspective. That's why black and white morality is faulty.