The insertion of alien faces in ancient imagery?

Again, in this book, there are images, from old art-works, that contain what appear to be faces of those damnable little gray beings that UFO witnesses keep seeing.

This is The Wheel of Becoming (19^th Century Tibet) [Page 400];

 The “alien faces”?

This is Yama and Yami, The Lord Death and his Shakti (19^thCentury Tibet) [Page 409]:

The “alien faces”?

This is Chakra-Samvararaja and His Shakti, Vajra-Yogini (18^thCentury, Tibet) [Page 404]:

The “alien faces”?

Did the creators of these works see little gray beings? Or did they have a neurological epiphany?

N.B. No, they're not impressions of skulls; they have the flame of life on their tops

RR