Chazelle has Been Mid After Whiplash

Agreed. He seems to have only one story he can tell, that of a young, deeply passionate artist trying to get their foot in the door while sacrificing other forms of happiness in the process (FYI, First Man wasn't written by Chazelle). He tries mixing things up by using different genres, ranging from psychological drama (Whiplash), musical (La La Land), and even satire (Babylon), but the core themes and ideas in his films feel really similar and derivative after a while, and even his choices of aesthetics wear out really fast (bright, saturated colors, ever-moving dolly in/dolly out shots, jazz laden soundtracks etc).

I don't know whether if he's just too obsessed with his own brand or if he just doesn't have enough life experience to tell more than just one story, but whatever the case, he needs to grow beyond writing the same few characters in similar story after similar story. He needs to find something deeper and more profound to say than just "he/she became a star, but at what cost?" over and over again.