Thank you, Abram Pinto. My USB-connected WebCam already appears in the Imaging Devices category, but the only camera listed in the Cameras device category is the Intel AVStream Camera 2500 that is built into my laptop.
I disabled the built-in camera because some apps would only draw video feed from it, and I could not get them to use the external camera without disabling the built-in camera. After I disabled the built-in camera, the apps would then draw a video feed from the external WebCam.
Is there any way to make the WebCam show up in the Cameras category?