What lessons should have been learned and implemented from the rise of Hitler and the Nazis in their ascension to power to prevent a recurrence of similar actors and ideological campaigns in future?

If you're talking about the US, they certainly aren't punching hard enough then. Trump is an extremist and basically leading right wing politics.

i can only speak for the western world since that's what i learned about as an american and there's a recorded history of punching left significantly harder than punching right.