In "Man and People", Ortega discusses the dehumanization of art, which is made confusing from his repeated switching between speaking literally and speaking philosophically, and by virtue of his work being a translation rather than the original Spanish copy. So, what exactly does Ortega mean when he calls art dehumanizing?
I think there are two main elements or aspects to Ortega's 'The Dehumanisation of Art' (La deshumanización del arte e Ideas sobre la novela, 1925; Princeton tr., 1968).
The first can be illustrated by a passage from the book :
A great man is dying. His wife is by his bedside. A doctor takes the dying man's pulse. In the background two more persons are dis covered: a reporter, who is present for professional reasons, and a painter whom mere chance has brought here. Wife, doctor, reporter, and painter witness one and the same event. Nonetheless, this identical event-a man's death-impresses each of them in a different way. So different indeed that the several aspects have hardly anything in common. What this scene means to the wife who is all grief has so little to do with what it means to the painter who looks on impas- sively that it seems doubtful whether the two can be said to be present at the same event' (1968 : 145).
The dehumanisation here, which has nothing negative about it, is the artist's emotional detachment from the scene - 'psychic distance' in one sense of Edward Bullough's phrase.
The second element or aspect is significantly diffferent, or seems so to me. It centres on the use of the artistic image - in poetry, painting or whatever - to 'denigrate' human lived experience. For instance a poet might use the image of a paperclip to describe the appearance of a bent and frail elderly person. The image is fresh but the result is to denigrate the person or whatever the object - it's to say, really this person is less significant than the image I use to describe her or him.
Another aspect of denigration unfolds. A long poem might be written about the contours and texture of (wait for it !) a human wart; an entire wall might depict a toe-nail cutting. Such art pulls us down to consider what we normally take to be beneath our notice or what we regard as distasteful or repellent. 'You humans might create great beauty but you also have warts and toe-nail cuttings. Don't think too well of yourselves' - these are not Ortega's words but if I'm right they express his attitude.
Ortega is a difficult writer; and his ideas changed. But this is my best effort to explain what I think he meant by the dehumanisation of art. What I've got wrong or omitted, doubtless other answers will correct and supply.