It isn't really chopping and changing though - that is how inheritance and dynasties work - pure accidents of birth.
For example, I inherited a very small amount of money a few years ago for my dad's cousin - a man I had never met, nor knew nothing about. It is what makes family trees and genealogy so interesting. Even in two or three generations your branch will have changed and moved on from that of a second cousin.
I would say that the last time the royal family 'chopped and changed' was when Queen Anne, the daughter of James II died. Her younger brother would have been king before both her and her sister, but was excluded because he was Catholic - as it happened that particular line died out anyway as Bonnie Prince Charlie was the last in the line and had no legitimate descendants. When Anne died in 1714 the throne went to the closest male Protestant relative she had - George 1.
Of course the current monarch would be a totally different person if the law had always allowed the first child to be the next in line - male or female, and if it had not excluded Catholics.
But the OPs assertion that Queen is German is simply not true.