Clans and group of people keep these skills to themselves.  MC is common person that some how got plot armor and gets random treasure skills from ancient or dead people's skills.
Gets a powerful skill from some cave that lets him go underground anywhere to attack.  Goes to poison old man and kills him.  Then MC heals his girlfriend with his op skill.  Enemy shows up, MC pretends to be old poison dude, they want to cure the arrogant kid that got his genital cut off, enemy gives MC very rare herbs, 2 groups of people fight each other, MC escapes with girl.