High Art
https://en.m.wikipedia.org/wiki/High_culture#High_artArt house:
A cinema which specializes in showing films that are artistic or experimental rather than merely entertaining.
Or
Used to refer to films that are of high quality but may not be extremely popular or successful.
Often times "high art" usually's created with the intention to primarily entertain but gets value attributed to it over time, whether it's expertise in the text or various readings of the subtext.
It all gets particularly muddy when you bring other non-western or non-wealthy opinions for example, into the mix, people ask why's Alien not counted amongst high cultural works? William Shakespeare's plays, once thought of as nothing but low brow entertainment, now hold a firm place as high brow entertainment.
But it is in theme primarily, while rarely meditated upon enough to give a definitive answer, the word play acted as an entertaining vessel for the musings- although apparently not intended to become a great philosophical thing- it did. Much the same's applicable to Alien I think, and will only increase in the years to come as it's groundbreaking qualities get re-examined over and over again.