No, it does not endorse it, mere recounts it. Claiming it is endorsing incest is a bit like saying Agatha Christie endorses murder.

There does not seem to be a clear interpretation of this AFAIK. A lot of the other bits of Genesis have clear messages (e.g. the creation myth, the near sacrifice of Isaac, etc.) but not all necessarily. It might be that there were no other men and they were desperate for children.

Endorsing or not doesn't matter if it's still "sexual content".

Re-quoting:

> Since its passage in 2023, Florida schools have removed hundreds of books under House Bill 1069 (HB 1069). HB 1069 required that school librarians remove materials from their collections that contain “sexual content,” regardless of the value of the book.