i mean he is a orchestrator, conductor, and the director in his life deciding the fate of his victims. If he is the silent sniper/artist/hand telling u cant do this and stop there when someone is trying to all in a ally, wouldnt it make sense jg role is more of a logical role than adc from that perspective lorewise. 
Jhin wants you to know he's the one that killed you, though. You're his artwork, his masterpiece. He wants to be close to you so he can see the light in your eyes dim as life vanishes from your body and hear your last feeble breaths. He wants to see the blood rush from your wounds, to see your body twist and contort into something horrifically beautiful.
People do take Jhin jungle(I do it all the time in bots), but it's not the best decision in the world. He could very easily be killed by the vast majority of the jungler cast, and his low mobility means he won't get around the jungle as fast as say Kayn or Rek'Sai. Also, Jhin doesn't like getting his outfits dirty. Why on earth would he ever go into the dense brush and river of the jungle and risk getting dirty?
