If the subjects of Ymir are the descendants of Ymir, and the only race capable of turning into titans, how's that Eren doesnt have royal bloodline?

Question

According to,

Subjects of Ymir

The Subjects of Ymir (ユミルの民 Yumiru no Tami?) are an ethnic group descended from Ymir Fritz and the only race that was capable of becoming Titans

Since Eren is capable of turning into a Titan, he has to be a descendant of Ymir Fritz.

According to,

Founding Titan

Only those with royal blood—the Fritz or Reiss royal families—were able to use the true power of the Founding Titan

So, how is that Eren isn't of royal bloodline, if he's a descendant of Ymir Fritz, who is the first ancestor of the Ymir royal family?

Answer 1

Subject of Ymir doesn't mean descendants of Ymir, it means all Eldians born after Ymir's titan demise, and the ones that lived in that time.