Literally was my thought

Well to get a skill requires ardent and daily cultivation of said skill most likely. For him to develop a killing skill, he'd have to kill constantly day in and day out. Which would make him a mass murderer rather than a lowkey old man. He kills out of caution not to be caught.

So then if he dreams of being a butterfly or some other flying animal, will he somehow gain the ability to fly? If so how will he go about it? Will he grow wings?

So by the logic he explained "doing" and "not doing" is mainly differentiated through intent. The intent to do something and actively trying to achieve results through said intent.

I cant be the only one that saw thar be has a disguise skill right?

Hes disguised obv.

Nope. He has always been mysterious origin.

I think because its an auxiliary skill that requires using an actual person to practice on, even if he had mastered how to use it, he still wouldn't be as proficient as someone who has been using it for an entire lifetime. His cheat cant create life like creatures that he can use to communicate with thus he cant rlly practice the sound transmission skill properly with his cheat.

Prob not. My assumption is that MC is not only a reincarnator but also a transmigrator. She probably regressed to an alternate past where the MC has become a variable that did not exist in her original timeline.

Thats why its considered honorable. Precisely because he didn't go the obvious and easier route. If he did, the word "honorable" wouldn't even be mentioned. Doing what is "expected" has never been used alongside the term "honorable".

Gonna need to have a lot of material from the start.

technically its not the longer his life is the more demonic he will be, but the longer his lifespan is. His lifespan does not represent his actual length of life. it represents his potential for life. He can die midway.

Having a clear state of mind has nothing to do with revenge and stuff. Its a matter of letting go and moving on. The MC is kind of narrow minded tbh. Revenge is typically the goto answer since its often the easiest one that people opt for to ease their mind of guilt, anger, and hatred and stuff but its usually not enough anyway. At least irl. But the concept of "Justice" still has its place irl. Thats become kind of a midway point so not everyone seeks out vengeance in a civil society.

Dayue

*Junior Sister*

live performances

You're forgetting its a fantasy. Perhaps Undead might appear in the future. It gives possibility to the idea that the MC can continue to exist without his muscles, perhap even without a body. None of those are unexpected in a cultivation story.

Could've just said coins. No need to specify copper. By claiming it was somehow shaped into copper coins, it implies alchemical processes of turning jade into copper and shaping it into coins which would make no sense logically or economically.

Is the setting Modern times?

Well thats a nice cope of an explanation I suppose.