DALL-E 2 does support 'inpainting' and 'uncrop' (zoom out, synthesizing edges) functionality which can be used to edit AI or human-generated images. I don't think OP used any (at least wittingly): one of the ones I looked at in OP were ones I recalled as inpainted/uncropped, those are relatively unusual compared to pure generation, and it'd be a bit unfair to include any.
From the videos I have seen of it in use, there is no way the prompts had existing material. One prompt was “painting of a goat in the style of the Mona Lisa taking photos with an iPad”. And it spat out 10 images which showed exactly that.