So, every Japanese knows Karate? That is what you are suggesting. Otherwise, he is not part of the Japanese culture.

My argument isn’t flawed. You just decided to limit your use of your brain for some unknown reason, otherwise, you would have asked yourself how cultures came to be and how they developed through the centuries.

How did the Pasta come to be? What about the gunpowder? The papyrus? Are we allowed to use paper without the express permission of Egyptians? Are the people living in Egypt today, the direct descendants of the people who invented the papyrus? Are they the authority on the use of paper?

Have your identity stolen then come talk to me about how ‘everything is everyone’.

Are we living in stupid-land, now? If I bought the necklace in your example, have I taken the identity of some far off descendent of the culture who created it? If I create similar necklaces, would I then be guilty of theft?

For the last part: yes. Everything belongs to everyone. Unless you yourself created something, you have no claim for its creation.