@Perun said it very well.
There is no population or ethnicity which is all red or redish. In some area procent of red or ginger people is higher then in others area. But there is no connection between them in recent past. For example you have Afghan and Yazidi ginger people but you have Scots. Their only connection is Indeuropean heritage. My family from father side is mostly ginger. Even i have ginger beard. But i cannot said that is a trait from Scandinavia or Rus or Scotland. Who can tell… Very interesting is that redish trait.
For me it is interesting how is Perun and Thor depicted. Strong lads with ginger beards. Maybe that symbolism was important for early Indoeuropeans.