Don't forget the Biblical view of human nature, that although we reflect some of God's attributes because we are created in His image, these attributes are distorted by sin. But that in Christ, we receive a new nature. This is more convincing to me than those two other views :-)
Just a minor point. "conservative" has to be studied in a particular context; otherwise, it's going to cause confusion. For example, in many socialist countries or former communist countries, conservative refers to ultra-leftists. But, in the West this term usually refers to people on the political right. So, make sure you clearly spell out the context of the term.
You need to be careful using an expression like "human nature." Part of the problem is that many decisions are mediated by consciousness or ideology and have nothing to do with nature. At the same time, Che Guevara projected the idea of "socialist man," which has a "human nature" (if you want to call it that) which differs from its opposite. The other base of comparison relates to historical anthropology of the sort offered by Kropotkin in the book, "Mutual Aid." John Gerassi's book, "Venceremos" will lead you to the Guevara essay. Given that individuals differ so radically despite a similar "human nature" and that these differences are more important than similarities, one might question the value of the concept "human nature" itself in its ability to answer various questions. I honestly believe that the very concept of "human nature" is misused as a substitute for other concepts, e.g. consciousness, social position, social structure, etc.