“Kami” means spirits. Every nonliving thing has a spirit. The tree, the rock. They flow through us, bind us to the spiritual world. That said, kami are kinda dumb – they aren’t stupid, it’s just that being the embodiment of a rock doesn’t lend itself to complexity. Shugenja can talk to this through rituals and stuff.
Souls =/= spirits. Living things and nonliving things have different places in the Celestial Order. This leads to some quirks, like the Celestial Dragons who are thus not technically alive.
A “daimyo” is the leader of an important clan, the head-of-household of the head-family of a clan. Cream-of-the-crop, top-of-the-heap, up-of-the-crust, there-can-be-only-one. His or her word is Law to the members of that clan.