Sorry. You are wrong. When a man has a son and is given the same name as the father that son is a junior.
When a grandfather has a son and is given the name of the grandfather, the son is either III or II. If all three men have the same name the new kid is III. If only the grandfather (or uncle) has the name then the child is II.
You can call yourself whatever you want, just like Obama, but if your father and you have the same name and your grandfather has a different name, you are a junior, not II.
This convention is important if you are into genealogy. So many of our ancestors had the same name and many lived in the same house. Getting mail was interesting. The difference between Jr. and II was very important.
Good nuff for nobility and this common folk alike. Tempest in a tea pot moment. LOL.
https://m.youtube.com/watch?v=FFNoDsOmluA
Cheers…. Hoot