How can I rig this 2D character so I can animate it without warping

Question

So I want to rig this 2D character made of unity squares to be able to animate

The Character

I want to rig it like this:

Rigging idea

They were all made by getting cube scaling them and then arranging to make the character I was going to group upper leg to lower leg but it warps weirdly

Warping

I don't know what to do

I tried just living with it and rotating it on the x, y or z-axis to check but all rotations are only on the z

Im clueless

Sry the images are wierd