Especially since Orochimaru had also conducted an extremely thorough, in-depth analysis of White Zetsu cells.
How should he put it...
White Zetsu cells were practically a smaller version of [Hashirama cells]!
Orochimaru even somewhat suspected that White Zetsu might be biological weapons created using [Hashirama cells]!
Otherwise...
Why were White Zetsu so compatible with Hashirama Senju's power?
Of course that's because Madara Uchiha really did mix [Hashirama cells] into White Zetsu's bodies!
Black Zetsu grumbled inwardly.
The creatures known as "White Zetsu" were actually humanoid puppets Mother had created using [Infinite Tsukuyomi] a thousand years ago, and their original forms were humans from a thousand years ago.
It was only after hundreds upon thousands of years of passive "cultivation" by the God Tree-primarily the Demonic Statue of the Outer Path-that these humans had taken on the appearance of White Zetsu.
These could be considered "First White Zetsu."
Several decades ago, roughly speaking...
Before his death, Madara Uchiha had merged Indra's and Asura's chakra, resonating with and drawing out the Sage of Six Paths' power.
He had successfully awakened the [Rinnegan] and summoned the Demonic Statue of the Outer Path, incidentally also "summoning" the White Zetsu from a thousand years ago.
Perhaps, in Madara Uchiha's eyes...
The so-called "White Zetsu" were humanoid puppets he had created by combining the Demonic Statue of the Outer Path's power with Hashirama Senju's cells.
But in reality, before Madara Uchiha had "created" White Zetsu, they had already existed for a thousand years!
Still, credit where credit was due.
After merging with [Hashirama cells], White Zetsu really did perform better than the "First White Zetsu" of centuries past.
They could tentatively be considered "Second White Zetsu"...
The living White Zetsu Black Zetsu had previously delivered to Orochimaru were all these "Second White Zetsu."
"White Zetsu can