going away vs human activity

going away and human activity both are nouns.

Word	Noun	Adjective	Verb	Adverb
going away	Yes	No	No	No
human activity	Yes	No	No	No

As nouns, human activity is a hypernym of going away; that is, human activity is a word with a broader meaning than going away:

Other hypernyms of going away include act, deed, human action.

going away (noun)	human activity (noun)
the act of departing	something that people do or cause to happen