@Olivier5,
By definition a "free world" doesn't need or have a leader, except when it is seriously threatened by an external force, That was indeed the case after WWII, as most of Europe was awash in the devastation and destruction of two major Wars and the proximate threat of an expansionist Soviet Empire, then in the process of swallowing up most of Eastern Europe and threatening the former European Empires. The role of leadership fell by default to the United States, which had been historically reluctant to get deeply involved. We did our bit to help restore European economies and lead in the defense to a then threatening Soviet Empire. All that ended in 1990, and, within a decade, the U.S. began reducing it's former role in leading international affairs - a process that continues.
I am a patriot of my country, as I assume you are of yours and/or the EU. Beyond that I don't have any need for domination or leadership of others, and I believe that view is widely shared here. Oddly you, hear, appear to exhibit some of the jingoism of which you accuse others.
Europe never conquered the "whole world" as you claimed, and didn't hold on to what it did seize for very long. It's sole leadership in science vanished a long time ago,
I agree that science often leads to better solutions, but it is done by humans and sometimes involves folly. The EU' s "courage to face global warming" hasn't so far accomplished much with respect to that phenomenon, and the methods so far used don't yet provide a real solution. The wind turbines and photovoltaic solar cells so far used won't yield much more at tolerable economic cost. The United States has reduced its GHG emissions ~5% in the last decade, mostly through profitable additional use of domestic natural gas. A real solution will require new technologies, say solar powered production of free hydrogen, or more acceptable applications of nuclear power. That said, you are free to march on courageously as you say ( and continue taking credit for the French commitment to nuclear power).
I don't think that Brexit is a triumph for the EU, anymore than is the current situation with the flood of hard-to-assimilate immigrants from the South. Indeed I believe these are indicators of internal political contradictions which persist in other areas of the Union. These are typical of the challenges most modern political systems face, but they are indeed real. That was the meaning of my statement of what lies ahead for the EU