The problem is that, if Zoro is Ryuma reincarnated, he didn't do any of those things Ryuma did
slaying a Dragon in Wano
making the Marines go away from Wano
so it doesn't work at all
at the end of the arc, the one compared to Ryuma was Luffy, not Zoro
so this doesn't work
Luffy didnt slay the dragons head off either. The Luffy Ryuuma shit is so fucking stupid, but the warning signs were there when Oda let Luffy wield the Nidai but never let Zoro have it and then it disappeared for the rest of the arc too.
Oden gravely wounded Kaido with both of his swords too but Zoro only got one of them via comparison so he was working with a reduced version of what Oden had too ofc, hence we will never know if he could do the same feat, given he didn't wound Kaido to the same extent either.
We obviously were meant to get those moments too but Oda didn't care and wanted us to suffer. The point would be all of those would have happened and Zoro would be Ryuumas reincarnation and or relative too but Oda didn't care to give us that.
I still stand by my own statement that he fucking hates us.