Firstborn
This meaning that regardless of gender any firstborn child of the heir is in line to inherit the throne. Additionally, if there is a younger male he is no longer instantly the successor. The royals have modernized with the times and are up to defeat the patriarchy.

Firstborn
Their Baby
Harry and Meghan on the other hand, have chosen to reject titles involving their son Archie, they want him to get a bit older before this occurrence. Archie most likely would have been Earl of Dumbarton, this title is currently held by Harry in Scotland. For now, baby Archie will be referred to as “Master Archie.” Once the Queen passes on this is all subject to change as everyone moves up in succession and change is inevitable. Charles will become King and William will be the heir to the throne.

Their Baby