Although not a conservative, I have sincere respect for conservative thought, because I think its core insight is human limitation. We human beings are too frail cognitively and morally to change societies wholesale without bad consequences.
You can come to that insight from a religious background, thinking that human beings are sinful but that we receive invaluable guidance from the divine. You can be completely secular, like Friedrich von Hayek, and argue that people lack the cognitive capacity to understand or manipulate something as complicated as a modern society, so we shouldn’t try to manage it centrally. Or you can be a cultural traditionalist, like Edmund Burke, and presume that much trial-and-error is embedded in all local traditions, whereas novel ideas are likely to go wrong, especially when imposed from without or above.
Regardless of your entry point, the conservative premise of human limitation leads to certain biases or tendencies: against central governments, against radical reforms, and in favor of durable constitutions, markets, and common law.
Of course, there is another side to each of those arguments, and I often land on the progressive rather than conservative side. (Just for instance, I don’t think that modern capitalist economies are really distributed systems that avoid top-down control; I think they are disruptive forces run by a few arrogant people.) But the conservative perspective is always worth serious consideration.
By this light, Donald Trump is not only the least conservative candidate in the current field, but the most anti-conservative candidate I can think of in modern American history. His whole argument is against human limitation. He promises that he can make everything radically better by applying his own amazing brainpower. He acknowledges none of the constraints prized by conservatives: religious revelations, cultural norms, constitutional checks, limited government in a mixed economy, or common law. I think his strong support in the primaries underlines the fact that the Republican electorate had become anti-conservative in basic ways, although a genuinely conservative GOP core is horrified by his campaign. As they should be, because he is the diametrical opposite of what is most valuable in conservatism.