Xin is not op. He is just really easy to play. The easiest champion IMO
He is pretty straightforward just turn q/w on them e someone.
I learned how to play with xin. He can dive and do all that good stuff without much skills, so he looks OP but at the end there are better champions, that can do more than xin, because after Eing someone and doing your ulti there isn't much he can do. I think that lee sin and irelia are better carries. Lee has more CCs, he can shield a allies to run away and he gets a lot of life steal with his shield. Irelia has a stun/slow, she has a ranged(sorta aoe) ulti, she deals true damage and she has a life steal passive( w or e idk gives her a life steal passive).