You don't need much. In fact you can begin making your game without knowing anything.
I heard that Brandon Sanderson gives good talks about how to write interesting narratives, this type of video would be your first study material.
Secondly, Ren'py is not hard, you just have to remember certain commands, if you want to tweak the engine and do something more interactive as some games here do you will probably have a little more work, but nothing you can't manage to learn on your own.
You use Ren'py to make visual novels (mostly) so I recommend you write separate documents for each of the character routes or each story turn you have in your game, be aware that the more you want to complicate the story the more work you will have.
For music you have a lot of free tools to create your own songs, you need to define what type of atmosphere your game will have to find the most appropriate tool, alternatively you can pay someone to do a bunch of songs that fits the mood of your game or you can get 'free for commercial use' songs.
Art is a little bit harder since you would need to put some hours into practicing it to do everything in your game. There is a lot of Youtube channels that teach art, Proko, Kienan Lafferty, MortMort, Draw with Jazza just to name a few. This goes for traditional/digital/3D art. As with music you can also pay someone to do your art or use 'free for commercial use' art.