How do i Make a custom "StarterCharacter"?

I'm making a game where you don't play as the default player model and I was wondering how you change it. I have seen tutorials on YouTube about how to do it (https://www.youtube.com/watch?v=AMk-pBlxgNQ&t=106s

but whenever I'm animation the rig I cant rotate the body parts. If anyone knows how to solve my problem or even just another way of making custom player models please tell me.

Thanks.

You cant animate it because theres a missing a part called Humanoidrootpart