Well, we did gain perspective in our intervention after World War Two, but we were plenty interventionist before that, in our realm of influence. Under presidents before World War Two, starting at least with Teddy Roosevelt, we were extraordinarily aggressive in Latin America. Countless coups, invasions, interventions, threats.
And we were actually a major superpower well before World War Two as well. World War two just propelled us to the top, and gave us motivation to stay involved. By the time of World War One, if I recall correctly, we had as much industrial capacity as Britain, Germany, and Russia combined. Our economy was massive, and the only prevention of us extending our power was our isolationism and self-absorption. World War I thrust us temporarily in the European system, we retreated, and then World War two made us one of the two superpowers.