I’m explaining that he’s shimons son through dina”
This is difficult to accept in a literal sense. Gilui Arayos is one of the sheva mitzvos Bnei Noach also, not just a mitzvah for Jews. How can there be any explanation that makes it okay for a brother and sister to conceive a child together, i.e. Shaul? I cannot see how Shimon and Dina had a biological child together. What am I misunderstanding here?