Mortals Kill Immortals and Achieve Enlightenment by Killing Immortals

[Having a female protagonist is not a harem, not a routine, not invincible, not a system, not brainless. Those who mind, beware. Immortals are immortal and powerful, and all living beings are attracted to them. There was an ordinary boy who aspired to become an immortal. However, those who cultivate immortality all harm sentient beings for their own sake. Later, there was a mortal who killed immortals and became enlightened.