> Conservativism largely fails over time in the free marketplace of ideas as evidence by human progress and societal change.

This is obviously just selection bias. Everything that changes is a loss for "conservatism"; ignore everything that stays the same, which is the majority of everything.

Here are some "conservative" (i.e. longstanding existing) policies: Due process, separation of powers, warrant requirements, freedom of speech. They are currently under attack. But the attackers are the ones on the wrong side of history -- even if they succeed, they lose, because then the monsters these policies were established to vanquish return and the polices get reinstated once the current generation has had a taste of what happens without them. But that route is a lot harder and bloodier than learning from history.