> I feel like because the USA has made mistakes,...

The Iraq War was not a "mistake", as you suggest. The Bush administration launched a war that killed between 200,000 and 1 million-plus people (depending on whether you strictly count bodies, which tends to under-count the reality, or you extrapolate from random samples of the population). This war was based on the claim that Saddam Hussein tried to buy uranium yellowcake from Niger, and this claim was based on a set of documents that were proven to be forgeries: "Mohamed ElBaradei, then head of the International Atomic Energy Agency, told the UN Security Council that his staff and independent experts concluded within hours that the documents were forged. They were printed, after all, on obsolete Iraqi and Niger letterheads citing officials who were no longer in power at agencies that had been disbanded. One letter, dated October 10, 2000, was reportedly signed with the name of Allele Habibou, a Niger Minister of Foreign Affairs and Cooperation, who left office in 1989." [1].

This wasn't a "mistake". This was either incompetence past the level of recklessness, or malice.

The most charitable explanation I've heard for why the US launched the 2003 Iraq War was that the Bush administration knew that steamrolling a weak adversary like the Taliban in Afghanistan wasn't a sufficient show-of-force to deter a well-equipped adversary from attempting another 9/11, and they needed to demonstrate the ability and willingness to attack a more powerful adversary (such as Iraq) to produce such deterrence. The least charitable explanation is the one we're all familiar with- that Bush, Cheney and Co. wanted to install a regime who would provide a steady stream of oil at friendly prices. The reality is probably a mix of both, as well as other explanations that we'll never be privy to.

Any way you slice it, the U.S. has proven itself incapable of delivering on its promises of regime change and nation-building since since at least the Vietnam War, yet keeps telling itself that "this time we'll get it right". The end result is that, trough our callous disregard for human life and the autonomy of others, we end up creating multiple terrorists for each one we kill.

> ...people jump to a defeatist attitude and take the position that literally anything we do is a mistake by definition.

This is a straw man argument; no serious person is taking the position that "literally anything we do is a mistake by definition". That said, if you're serious about winning people over, a good place to start might be the folks who were responsible for our "mistakes" giving even the faintest hint that, yes, we acknowledge those things we did were wrong. If we really want to go crazy, we could even (gasp!) commit to not repeating those "mistakes" again. But certain people in this country seem to believe that never admitting to a wrongdoing is the same as never having done wrong at all. Therefore the default posture seems to be "Often wrong, never in doubt". That's a recipe for flushing our reputation on the world stage down the toilet.

EDIT:

Lastly, just because the Marshall Plan was effective in Western Europe, doesn't mean it would be effective in Saudi Arabia or Venezuela. Please don't make the mistake of thinking all cultures respond to incentives in the same way. That's just wrong.

1. https://spyscape.com/article/saddam-husseins-fake-uranium