In the end, Jack doesn’t seem that damaged, he swallowed all that impact from Zunisha’s trunk.. what a beast!
He also look even more of a beast without his mask. So Jack is a Fishman? Too bad he can’t swim anymore because of DF , anyway he is able to breathe underwater.
Also now that everyone left, it’s a perfect opportunity for him to go back on Zou. It seems that Law and Zoro already left to boot, only leaving Inuarashi as capable one and even him doesn’t seem to be in that great of a state. What if he ends up capturing Momonosuke?
Yes.I think he is a fishman or merman.Because only fishmen can breathe underwater after eating devilfruit because of their gills.And you can see that he is immobilized.And also his teeth represents fishman like arlong etc…
Jack is also wounded from his attempt to rescue Doffy