Per Wikipedia, the US has been involved in over 400 foreign interventions in its history, roughly half since WWII. So off the top I'm not arguing that most of these were net positive. However some were, a few quite spectacularly.

The first two are often overlooked because they've been so normalised: the US occupations of Germany and Japan in the post-war era, including the Berlin airlift which preserved the status of West Berlin, establishing new democratic governments in both countries and exceedingly vital economies, with both countries becoming powerhouses of the post-WWII global economy, as well as major trading partners of the US. As a post-conflict treatment by a conquering power of defeated enemies, this is exceptional in all of history, let alone the past century. I'd argue that in some ways this success possibly doomed or haunted other missions as the European and Japanese occupations were so successful.

Other post-war occupations and/or liberations include Italy (as with Germany, occupied by the Allies), also setting democratic governance and a successful economy, and the Philippines, which gained independence from the US (after being liberated from Japanese occupation) in 1946.

The US was a major participant in the Korean War, which prevented the Communist takeover of South Korea. Though South Korea was not especially democratic until the 1980s, it also fell under the US trade and economic umbrella and emerged as another Asian powerhouse economy.

The US assisted in the formation of Taiwan as an independent state and through military security guarantees has maintained its position against an aggressive PRC which continues to threaten independence to this day.

During the Greek civil war, the UK and US supported the Greek government against Soviet-backed rebels, under the Truman Doctrine, keeping that country in Western Europe and out of the Soviet Bloc.

The UK and US were also key players in establishing the State of Israel, which is admittedly something of a mixed bag. Jews gained a homeland, Palestinians lost one. The present State of Israel is quite arguably engaged in a genocide against the Palestinians, as many Jewish and Israeli critics of the government will argue quite persuasively.

The US-lead first Iraq War in 1990-91 to liberate Kuwait is another case of a largely justified and successful operation.

The 1990s also saw peacekeeping operations in Somalia and Bosnia, and acting with the UN, a mission to reinstate Jean-Bertrand Aristide as president of Haiti following a coup.

Keep in mind that there are other actions in which the US has played key roles with diplomatic, political, economic, and/or military support through other allegiances or organisations, most especially the United Nations and the 70 peacekeeping operations it has undertaken since 1948. With its permanent seat on the UN Security Council and corresponding veto power, those missions inherently require the support of the United States as well as the other four permanent member nations: China, France, Russia (formerly USSR), and the UK. Peacekeeping operations have occurred in India, Pakistan, the Congo, the Dominican Republic, Yemen, Cyprus, Middle East, Lebanon, Angola, Cambodia, El Salvador, Mozambique, Namibia, Rawanda, Somalia, Yugoslavia, and elsewhere.

<https://peacekeeping.un.org/en/our-history>

<https://en.wikipedia.org/wiki/Foreign_interventions_by_the_U...>

That's at least a dozen, and possibly thirteen instances of positive engagement, excluding UN peacekeeping missions. There may be some other instances in the 200 or so foreign interventions. There are definitely interventions I'd consider net negatives, Iran 1953, Guatemala 1954, Bay of Pigs, Vietnam War (and related conflicts in Cambodia and Laos), Chile 1970-3, Nicaraguan Contras 1981-90, El Salvador 1979-90 most especially. Even in the case of the most egregious of those engagements though, Vietnam, the present relationship of the countries seems fairly good, which is worth pondering.

But to say that there have been no successful or positive interventions is simply not supported by facts.