To me, conservatism is the least ideological philosophy, because it primarily looks at actual results and bases its positions on common sense and practicality. Both liberals and libertarians get caught up in “bumper sticker” beliefs and try to reshape reality to fit their beliefs instead of focusing on what actually works.
Which part of their ideology do you think conflicts with human nature or practicality? Conservatives obviously don’t completely agree on the details of implementing their idelogy, e.g. the fair tax vs. the flat tax. But the idea of lower taxes and smaller government is based on years of observation about what seems to most benefit an economy. Likewise we support constitutional principles because they worked to make us the most successful country in the world. I think conservatism is more tuned to human nature than any other political philosophy.
What are you defining “human nature” as?