The purpose of the drawing canvas is to help you organize your drawing objects. There is another way you can create drawings, and that is by using what Word calls the 'drawing canvas.' You create a drawing canvas by displaying the Insert tab of the ribbon, clicking the Shapes tool in the Illustrations group, and then choosing New Drawing Canvas. All you need to do is click on the drawing tool you want to use, and then use the tool to create the item in your document. If you are creating the graphics yourself, the normal way to add the graphics is through the use of the Drawing toolbar.
Word, for quite some time, has allowed you to add graphics to your documents.