So I was thinking, all the Kekkei Genkai are non-living elements, except for Wood Release. Plus, only 1 person in the world obtained this Kekkei Genkai naturally (Hashirama). So I have this theory where Wood Release is actually not a Kekkei Genkai. My theory is that Hashirama found something that relates to the Shinju, he then sealed it in himself so that he gets chakra or something. Then he found out that he could create and control wood. That's why he's the only one that can do Wood Release in Senju.
Wood created from Wood Release can absorb chakra, like the Shinju and the Ten-Tails. These wood can also bind Tailed Beasts and deflect their attacks (Tailed Beast Bomb), similar to how the Shinju and the Ten-Tails survived his own Tailed Beast Bomb, plus this is something normal wood couldn't do.
The dragons and statues Hashirama summoned, could be the plant equivalent of a Tailed Beast (animal). Like how the Shinju is the plant equivalent of Kaguya (animal/humanoid) in terms of the structure of the Ten-Tails.