There are many ways to add layers to images. Create a new layer, promote the background to a raster layer, duplicate an existing layer, or make a selection and turn it into a layer. And when you use the vector drawing tools, the Text tool, or any of the Art Media tools, new layers are automatically created.
Ways to add new layers to an image:
Creating Raster Layers from Selections
Promoting a Background Layer to a Regular Raster Layer