In GoAnimate, a character is much more than an image. It is a collection of attributes, such as poses, actions, facial expressions, and mouth movements. All of these, and more, are what define a character, and they are programmed into each character set.
As such, new characters can not be uploaded. Instead, use the Custom Character Creator built into GoAnimate to create your very own characters right from within the platform.
Learn more about what types of files can be uploaded to GoAnimate.