Kind of sound intermittently faint (5)
I believe the answer is:
'kind' is the definition.
'sound intermittently faint' is the wordplay.
'sound' becomes 'hum' (hum is a kind of sound).
'intermittently' indicates alternate letters.
The alternating letters of 'faint' are 'an'.
'of' is the link.
(Other definitions for human that I've seen before include "Anthropoid" , "Relating to a person" , "Fallible - person" , "Man, woman or child" , "Being that's apt to err?" .)