human action vs event

human action and event both are nouns.

Word	Noun	Adjective	Verb	Adverb
human action	Yes	No	No	No
event	Yes	No	No	No

As nouns, event is a hypernym of human action; that is, event is a word with a broader meaning than human action:

human action (noun)	event (noun)
something that people do or cause to happen	something that happens at a given place and time
	a phenomenon located at a single point in space-time; the fundamental observational entity in relativity theory
	a phenomenon that follows and is caused by some previous phenomenon
	a special set of circumstances