I'm sorry, i understand where you are coming from..Again, I'm not arguing that he didn't have an ability contingent on not using hands seals.
What I'm saying is he has not feats nor does the manga say that he can create new cells (organs, tissues and limbs).
but eventually the burden of proof that Hashirama can't create new cells is on you, he can heal himself, what else do you need ? What does healing means ?
You can accuse us of appealing to probability (because we are taking something for granted since it would be the case because the manga points in that direction, not your/other way around) so this thread in my view is now just void of meaning and will have no conclusion, nor you will find what you seek.

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