Why doesn't the character model change?

[worthy quail]

Why doesn't the character model change?

[stable steppe]

make sure you use the model template for the version of the game you are using

!mobparts piglin_16

[onyx terrace]

Piglin [1.16]

head left_ear right_ear body left_arm right_arm left_leg right_leg

You can use the CEM Template Loader plugin to load a working template with the correct part names and pivot points.