Thomas Jefferson was the original neocon

[Southern Senator North Carolina Yankee]

One could argue that manifest destiny was something that could easily transition into imperialism or whatever.

I recently scanned an English-language book from the USSR with a chapter on the Manifest Destiny, making that point. Obviously one can disagree, but there it is.

The former represented the Hamiltonian faction who organized as the Federalist Party and later merged with Henry Clay's "National" Republicans to become the Whig Party in the 1830s—and by every meaningful standard, they represented the conservative element in the politics of their time.

To help substantiate that we could quote Clay arguing against Van Buren's claim that people looked too much to the government for help: "We are all—people, States, Union, banks—bound up and interwoven together, united in fortune and destiny, and all, all entitled to the protecting care of a paternal government."

The American System of economics that Clay promoted clearly had more in common with modern "big government" investments in infrastructure as practiced by FDR and JFK.

And yet, as you note, Clay represented the forces of conservatism in his time. Even Soviet historians classed Jefferson and Jackson as belonging to the left-wing of American political life in their times, whereas the Federalists and Whigs represented the right-wing.

For the time, conservatism was more about societal stability or national strength. It was very establishment oriented.

Conservatism was very much establishment minded until the mid 20th century and the process of the establishment being fundamentally reconstituted in the New Deal Era and reaction against it by emerging anti-establishment conservatism is a topic that Kevin Phillips discusses in The Emerging Republican Majority.