I as well have bought the game and can't select any option in the start menu.
It saddens me that such a major issue has gone unresolved for so very long.
It saddens me more that I can't even play a game I payed for.
EDIT: Less than a minute after typing this response I tried to interact with the starting menu and could not, I then wondered if the Nintendo Pro Controller (Wired Connection) I had to my computer was interfering with the inputs. While connected neither the controller or my mouse could interact with the buttons on the main menu. Once I removed the controller the menu could be interacted with as normal!
I hope this solves your issue!