No, Keynesian economics was the downfall of U.S (and the west in general) , real purchasing power since the New Deal has only gotten worse and worse.
You are putting the cart before the horse, people didn't want keynesianism, Keynesianism told politicians that they're NOT the ones at fault of economic struggles of each nation and in fact, if people gave politicians more power to increase the size of government, things would be better.
The progress that you saw afterwards was what we had, where you are wrong is in assuming that had it not been for such horrible economic policy, said progress wouldn't have occured...this is absurd, when we observe the transformation between 1700's and 1800's and then late 1800's to early 1900's , it becomes clear that Keynesianism substantially held back progress, if at least Argentina and UK would've stayed free countries with free economies, progress would've been much MUCH higher than it was in our shitty reality in which the entire western hemisphere went full retard.
I will admit, U.S was always going to go down this path, migratory patterns sealed their fate.
As for Europe, you're wrong and you admit so at the end of your reply.
The continental European view is just U.S American propaganda which you've been raised under, "you're all white Europeans so you're all like...the same xd" this is nonsense.
"Europe" can't be saved, because some parts of Europe's salvation will inevitably be another part of Europe's doom, because you have vastly diverse and different cultures and worldviews, trying to mesh it all together is a terrible mistake, reason for which the European Union is a failure and will be abolished in the next 2 decades.
You say you can't "go back" from the Union?? So Europe doesn't get to have Nation States???? But the American continent does? Afrika does? Asia does???
Besides you're telling me you'd like a Federation, which would essentially be an exit from the Union, and an introduction of a new Nation State [which would be terribly disfunctional].
I know you don't agree with any of this, but just entertain my crazy, crazy ideas in your head...and consider that all you were teached in your public schools might've been a load of horseshit...wouldn't it make history suddenly clearer? doesn't it tickle you a bit???