A straw man argument is one where you are misrepresenting an opposing position, so I don’t think the term quite fits here. I’m not trying to claim it’s never done anything good, but even the arguably good things have always been more about calculated self interest than any real concern for human rights or welfare:

en.wikipedia.org/wiki/Marshall_Plan

The purpose of the Marshall Plan was to aid in the economic recovery of nations after World War II and secure US geopolitical influence over Western Europe.

The only major powers whose infrastructure had not been significantly harmed in World War II were the United States and Canada.[30][31] They were much more prosperous than before the war, but exports were a small factor in their economy. Much of the Marshall Plan aid would be used by the Europeans to buy manufactured goods and raw materials from the United States and Canada.

WW2 left the country in a position of relative economic power, and in the following decades it used its greater influence the same way it had before (eg. the wars in Hawaii, the Philippines, Cuba etc.), to advance the cause of global capitalist exploitation and brutally suppressing even democratic opposition to it.

To me the main change here doesn’t seem like the US becoming substantially more evil than the already substantial evils of the past, just getting worse at acting coherently in its own interests, acting against its allies instead of just geopolitically marginalized victims.