They start with the assumption that England is the best and work backwards from there. The Saxon is only good when mixed with the Angles, thus they are superior to Germans for example.
The impression that Germans and Scandinavians are included is largely based on how things became later when you got national romance and especially since Germany have the dubious honour of being home to the most notorious race scientists and the notion of Aryans.
They start with the assumption that England is the best and work backwards from there. The Saxon is only good when mixed with the Angles, thus they are superior to Germans for example.
The impression that Germans and Scandinavians are included is largely based on how things became later when you got national romance and especially since Germany have the dubious honour of being home to the most notorious race scientists and the notion of Aryans.