1. I was wondering about some spells that say in its target description "one/a living creature".
Who does this work on exactly?
Does it work as well on:
2. Hold Person and similar spells that says they work on humanoids.
Do Shapechangers count as they have a humanoid as a base creature?
Many spells affect “living creatures,” which means allcreatures other than constructs and undead.
Undead are undead. Constructs are neither living nor undead (see the Necromancy wizard school).
Q2: Humanoid is a type, shapechanger is a subtype. A humanoid (shapechanger) is a humanoid, even when it's transformed into a different-looking shape. A shapechanger that is not a humanoid isn't affected by the spell, even if it's currently in a humanoid form.
So enchantment spells that work on living creatures (like Command) work on all non-undead, non-constructs that are not additionally immune to enchantment effects?!
I am not sure, but I suppose Oozes and maybe plant creatures are immune to these effects :D
I believe that they are as well, I believe by definition oozes and plants are immune to mind affecting abilities and spells, as they have no mind to affect.