I'm pretty sure Rey has flown before, including those ships that she was running for when the TIEs came. She's probably flown for the crime boss she was selling her salvage to, considering how much she knows about those ships (and her history of maintaining them, including the Falcon).
Also, she out fights (or at least matches) a fobbit who broke after his first combat mission. And Kyli Ren explicitly isn't a Sith Lord. He's powerful in the context of "random blaster armed Rebellion troopers", but against anyone who is reasonably powerful in the Force, and already wounded, there's no reason why he wouldn't be stomped.