Even grammatically it is illogical..

By that logic, a Chinese person, who descends from slaves of the Shang dynasty could
Move to America, become an American , and say that he is an American Descendent of Slavery. He is now American, and he also descends from slavery.

It should actually be Descendants of American Slavery....if we want to be grammatically correct.

But even still it’s a generic term that does not acknowledge my indigenous blood or my roots.

Also American is a nationality, not an ethnicity. So stop treating it like it’s an ethnicity.

This is why African- American is used...African being the ethnicity and American being the nationality.