A shape is basically a form that has a boundary. A shape is different than a texture in that texture would be within a shape; though textures themselves are shapes, perhaps shapes in color variation. The manner in which we talk about shape here, is that the edges are clearly defined and differentiated from a background, other object, or other shape can be a significant color change or a line. I suppose a texture can be thought of as a group of shapes that are part of a higher order and together represent something.
Text are shapes that are automatically recognizable and immediately interpreted. However, graphic artist know the font used in text can take many shapes and thus the arrangement and style can influence the perception.
In sum, shapes matter.