Sure, but WWII was a historical anamoly, not a "historical norm". "World peace", to my mind, implies _no_ wars, not just 'less conflict than the biggest war in history'.
Not as much as you might think. WWII was unusual, but not unprecedented. See:
https://en.wikipedia.org/wiki/List_of_wars_by_death_toll
WWII was not even the deadliest war ever, even in terms of absolute numbers, and certainly not in terms of percentages. (Note that that Wikipedia page inexplicably does not list WWI, which killed 38M.)
The last war to have a death toll over 1 million was Viet Nam.
> "World peace", to my mind, implies _no_ wars
On that definition there has never been world peace.