The model we imported was textured and rigged, so it came with a virtual 3D skeleton and images. Once we set the animation type to Humanoid, Unity was able to create an avatar linked to the rig.
The power of the Unity Mechanism animation system is that animations are related to avatars, not to the 3D models specifically. Therefore, we can apply the same animation to different avatars in different 3D models. If one character model is short or tall or fat or thin, or has long arms, and so on, it does not matter. As long as the rig has been appropriately created to match the locations of the 3D model, animation can be applied to the 3D model.
A GameObject Scene containing a character model has an animator component, and its two most important properties are linked to the avatar, and to the Animation Controller. We created a simple Animation Controller that starts with the idle animation from the Unity Standard Assets and uses the defaults for a transition over a short...