Nordic / Mediterranean - Chad Roman steps over a Nordic in chains

It's actually a very good question. If you want my honest opinion, it's probably based on an inferiority complex that Germans has, on the fact that they couldn't even record their own history until Greeks and Romans started doing it.
The same goes for the Britons and Vikings. The latter actually arrived in America centuries before Columbus, but they did absolutely nothing with their discovery and returned back home.
Hitler writes about this, and expressed his disappointment

The second is probably based on looks. I'm a Southern Italian, and I've been for at least 7 generations; When I was a child, I had blonde hair and blue eyes (now the hair turned brown), and while I did receive some compliments for my looks, I never saw my light blue eyes as a superior trait. On the contrary, they are very sensible to the light, compared to the members of my family who have brown eyes.
Usually a Nordicist will go on to praise these mutations and recessive genes because it makes them feel special, and while it is true that those genes aren't very common, they shouldn't be taken as a sign of strength.
Overall, I believe that that during the Industrial Revolution, countries like England and Germany taught to be superior over everyone else on a genetic level.

You forgot that the Great Finnish Empire that ruled over most of Europe.