How do RigidBody2D's inherit physics?

Godot 4.1.3 - 2D game

Hey everyone!

I’m pretty new to Godot now having recently switched from Unity, and I have a question about the RigidBody2D physics and what happens when they are the children of other nodes.

For Context
I’m remaking my 2D game jam entry where you play as guy climbing and jumping from left wall to right wall (it was a spoof for GMTK 2024). Originally, I used a CharacterBody2D to control the movement and found it wasn’t as smooth as I wanted. Here’s the original game if you’re curious. Don’t judge; it’s like my 2nd game in Godot.

Problem
I changed the game to be just an arm (because it’s easier and looks funnier). I’m trying to make it a rag-doll with rotation limits by using PinJoints, but I’m having trouble with adding an impulse to the parent and having the children follow. It’s glitchy. I don’t know if this is how I’m supposed to be using Godot’s RigidBody’s. Can someone help me understand this a little better? Also, I still don’t understand why RigidBody’s attached to a CharacterBody ignore physics, so I would love some help understanding how that works as well.

Thanks in advance!