Yes, of course, each of those countries is internally very diverse, and in relation to the others.
Each of those countries was made by a mix of native, European, African and Asian peoples of different kinds, in different proportions, at different times. Europe is made of just Europeans, and immigration is a very recent thing.
Is this what American education sounds like? Do you recall that European nations practically ruled the world at different times in history and gladly took in and integrated foreigners? Unlike Americans who mostly wiped out the natives and grandfathered in slaves.
So why were non-white populations in Europe negligible until about 60 years ago? Statistics are hard to come by, but do these pictures of London shortly after the fall of the British colonial empire look like a capital that "gladly took in and integrated foreigners"? https://www.vintag.es/2012/12/london-in-color-photographs-in...
Having been educated in Europe myself, there was no hint of this "gladly took in and integrated foreigners" you speak of in the curriculum. May I ask where you got this idea?
Each of those countries was made by a mix of native, European, African and Asian peoples of different kinds, in different proportions, at different times. Europe is made of just Europeans, and immigration is a very recent thing.