Pareidolia.
It's a common and very normal psychological phenomenon, in which the pattern-recognition function of the human mind "perceives" familiar patterns (or patterns that it's more motivated to discover) in objects of perception that bear only a faint resemblance to what's "seen". It's most commonly exemplified by "seeing" human faces in inanimate objects like clouds or rocks.
https://en.wikipedia.org/wiki/Pareidolia
A fascinating thing is that this phenomenon also occurs in computer vision programs. I would expect to see it in situations where 'neural networks' (whether organic or computer) are trained to detect certain patterns and become highly sensitive to them. With human beings, for obvious reasons it's other human faces.