What you’re seeing are constraints and, possibly, transform locks or disabled outliner selection. None of the things you have selected on your outliner are bones. They are meshes-- you can tell from the icon.
I’d strongly recommend making at least one rig from scratch to get a feel for constraints and transform locks.
Each rig is going to be slightly different in how its designed and how it handles. You’re going to have to learn how the rig you chose works.
While I’m not familiar with that particular rig, I’d say it’s unusual for rigs to be designed such that simply allowing a pose changes the pose. For the rigs I’ve seen, that can happen with editing the rig in a way it wasn’t supposed to be edited.