From my perspective, based on the books, and a little on the show. Rhaenys was next in line after Jaehaerys two qualifying sons had died with no male heirs. His wife wanted him to make Rhaenys his heir as she was the oldest (grandchild I think, and child to the oldest of Jaehaerys offspring). The meisters strongly discouraged adding a female as heir, yet there was nothing in Targaryen history that prohibited females from ruling. This was suggested as being an issue with Westerose tradition, yet there were multiple female rulers in Westerose, before and after Aegon the 1st had conquered those lands. Jaehaerys called the counsel, the first and only of its kind, because he did not want to make the decision himself (for a variety of reasons). At the time Rhaenys was either pregnant or had very young twins, depending if you go by book or tv series. Either way, given the rare choice to decide themselves, leaders were not going to support a pregnant female or a baby, when they knew their king may not live much longer. All of this is explained in the book, but people talk of it as if that counsel (which was a giant popularity contest) was the be all and end all of passing down inheritance of the throne in Westerose.
Rhaenys wasn't even close to being queen. She was only in the mix because her husband entered her name.
From my perspective, based on the books, and a little on the show. Rhaenys was next in line after Jaehaerys two qualifying sons had died with no male heirs. His wife wanted him to make Rhaenys his heir as she was the oldest (grandchild I think, and child to the oldest of Jaehaerys offspring). The meisters strongly discouraged adding a female as heir, yet there was nothing in Targaryen history that prohibited females from ruling. This was suggested as being an issue with Westerose tradition, yet there were multiple female rulers in Westerose, before and after Aegon the 1st had conquered those lands. Jaehaerys called the counsel, the first and only of its kind, because he did not want to make the decision himself (for a variety of reasons). At the time Rhaenys was either pregnant or had very young twins, depending if you go by book or tv series. Either way, given the rare choice to decide themselves, leaders were not going to support a pregnant female or a baby, when they knew their king may not live much longer. All of this is explained in the book, but people talk of it as if that counsel (which was a giant popularity contest) was the be all and end all of passing down inheritance of the throne in Westerose.