Most Kashubians besides being totally related to the Polish tribes (Western Polish Slavic),
Identity today isn't based on ancient tribes.
I had the utmost respect towards the Polish-Kashubians who clung on to their Polish identity and their PURE Polish language!
Some choose not to - that is their right. Hard to know what you mean by 'pure Polish identity' (why the capitals?) since Polish is a living and evolving language not an ossified ancestral one.. Were you to get a time machine and go to those tribes you mention you and they would have nothing to say to each other and no common recognisable language to do it in - even a few generations back, you'd have a pretty hard time making yourself understood.
I am descended from Polish Eastern Galician Noble Poles, who gave their lives to defend the Eastern Borders for glorius Poland
Aside from the fact that 'nobles' isn't a good translation of szlachta
who made up between 12 and 18% of the population, how would your relatives impact on anyone else's cultural identity or they on yours?