Too many years of bad improv classes means that when I am handed weird things and told to run with it, I cringe internally and wonder if I can drop the class and still graduate. "You are a half android half strix raised by dwarves! GO!" "Um... no? Do we have a pregen I can play instead?"Stop gatekeeping, Norgrim!
In seriousness, I find a full slate easier to roleplay than a blank one. Sure, you can add whatever you want to a blank slate, but that emptiness is daunting. It's why it's easier to start roleplaying when someone else has already entered the scene (and why an awkward silence generally follows when the GM says, "Okay, now roleplay for a bit").
You will take what you are given. There is no other cure.