Yeah, the J-15 is an interesting bird over and above the capabilities of the jet. China is well aware of their reputation (and realities) of only being able to copy/steal other people’s stuff, so they’ve decided to move away from copying (licensed or otherwise) and start working up their own R&D efforts - not incidentally reducing their reliance on Russia, who they may be at war with again soon. The J-15 is based on the Su-33 airframe, but under the skin, they’re using as much indigenous Chinese technology as they can. It’s a follow-on to the J-11B program, which was based on an Su-27.
https://en.wikipedia.org/wiki/Shenyang_J-11#J-11
https://en.wikipedia.org/wiki/Shenyang_J-15
“Indigenous Chinese technology” = stolen US technology