Why are animations always broken

So basically, I can’t create custom characters without Roblox’s animations collapsing in on themselves.
robloxapp-20200726-2157079.wmv (4.2 MB)
Like I said in the video, the model was scaled down and then each body part was turned into a union which I then named Torso, Head, etc. The HumanoidRootPart is an invisible clone of the torso turned 90° to stop the character from walking sideways due to the way the model was built. All body parts have a Motor6D including the HumanoidRootPart.
Any help would be appreciated! ^-^