Exactly. Every place was colonized by somebody else, and everyone had ancestors who were at some point brutalized, raped, or enslaved by someone else's. The difference is that most of us have the sense not to try and use this fact as a get out of jail card.
Celts and Saxons are actually some of the first migrants into early Europe. They also brought a lot of technology, such as it was. Farming, metal working, etc. Also being somewhat larger than Europeans at the time, they were a thing to be feared. Hitler’s vaunted “Aryan race” was not actually a race, showing that he was either stupid or a liar or both. They were connected by a common language, nothing more, from somewhere farther east.
The difference is that for the mix I think you're talking about, one does not have to do a DNA analysis to discover the tell-tale factor.
(just sayin')
Equally, we’re all descended from people who did the brutalizing, raping and enslaving.