I think diversity is much more than just the color of someone's skin. People from Sweden and Spain are very different even if both would be considered white, and if you have a 25%/25%/25%/25% group of Swedes/Spanish/Ukrainian/Icelandic, I'd still consider the group diverse even though all of them would probably be called "white".
Not everywhere, but certainly Europe is. I think you're focusing too much on the ethnicity and ignore the really important things like cultural and thought diversity.
Poland is literally 95%+ ethnic Poles (many of whom have their ancestral roots outside of Poland, but that was centuries ago - they consider themselves Poles now). It's not diverse at all, not "infinitely diverse".
