I never really liked the idea of "power levels", because they just seem really inaccurate. A character's "power level" largely depends on how a writer wants a scene to go for the most part, with power level playing a rather minimal impact. As Stan Lee once said, "The person who would win in a fight is the person the writer wants to win".
No matter the case, most of my characters are Wolf to Demon in power level, with one of the villains being Dragon level and the main one being God level, although I'd go ahead and see he's less of a "threat to humanity" and more of a "threat to the concept of reality itself". Despite this, they're all very capable of being killed, and every single character in my story can and will die extremely easily if the enemy knows what they're doing.
In my story's case, even if some of the characters are very strong and capable, they're still just twigs to be stepped on in the grand scheme of things. The only character in my story that cannot be killed by someone with some preparation is the villain, who, for all intents and purposes, is indestructible. But that's kinda the point.