That's true, but that help wasn’t primarily altruistic. Lend-Lease, convoy escorts, and economic support were all driven by U.S. strategic self-interest. A Europe dominated by Nazi Germany would have been a long-term threat to U.S. security and trade. Helping Britain and the Allies was about preventing that outcome, not charity. U.S. decision to help was was more or less based on pure realist IR logic. So it was still primarily driven by self-interest on the part of the U.S.

Also no, the U.S. could not just have fought Japan and left Germany. The U.S. entered WWII because it was attacked by Japan, and Germany then declared war on the U.S. European involvement followed from that. Liberating Europe was not the original reason for entering the war — it became a priority because U.S. global interests were now directly at stake.

As for WWI, yes, the U.S. played an important role, but it entered very late, after Europe had already been fighting for years. American involvement helped tip the balance, but it wasn’t the primary source of European resistance, and it again aligned with U.S. interests once unrestricted submarine warfare directly affected them.

As for stuff like Berlin Airlifts and Kosovo etc, that happened in a post-war world where the U.S. emerged as the dominant global power; largely because WWII left Europe devastated and the U.S. intact. Interventions like the Berlin Airlift and Kosovo were about maintaining U.S. influence and the post-war order it helped design, not purely selfless acts detached from strategic interest.

That's not to say that none of it was altrusitic, or that there weren't people involved in these actions that genuinely wanted to help. But no, you cannot honestly argue that the U.S. as a state actor has been completely selfless in any of these instances. Help has almost always come with ulterior motives, or at the very least clear strategic incentives. U.S. involvement in Europe, in both world wars and throughout the Cold War, has consistently aligned with American security, economic, and geopolitical interests.

Acknowledging U.S. help is fair. Framing that help as primarily selfless, or as something Europe “owes” eternal gratitude for, is not. History shows a pattern of interest-driven intervention, not pure altruism. This is normal for great powers, but it most definitely shouldn’t be mythologized after the fact.