It would be hard to argue that the United States did not win. Compared to its other major allies, it didn't suffer huge losses in life and didn't see its cities and countryside heavily damaged by bombing or invasion. It ended the war as a Super Power with expanded territorial holdings, massive military might, and a strong economy. (Regardless of the Cold War, and some later proxy wars, America continued to remain a rich Super Power)

one of the ''winners'' (Great Britain) had lost most of its overseas territories. The country was exhausted, it was no longer a world power (same thing can be said about France).

Tell that to the United Nations, where France and Great Britain still have permanent veto power over the Security Council. Even without overseas colonies they have the power to hold up the UN.

The UN charter marked Japan and Germany as enemy nations. Both countries have tried, in vain, to get similar recognition, seeing as they are arguably as important as France and GB. But the victors of the war have not been keen on expanding the security council.