Rebirth: I Have a Thief System

The protagonist is a time traveler. In this era where demons are rampant and human beings are weak and are slaughtered as a duty. Fortunately, Gu Changli lives in China. Under the rule of the government, people with superpowers who can resist other races have been cultivated. In this era where martial arts is respected, how will the plot begin? The author is a new book reader. It is his first time writing about time travel system. I hope you can give me more opinions. This novel and its characters are purely fictitious. Any similarity is purely coincidental and should not be imitated.