The below is not the whole story. And it's too overbearing to define a single starting point for the analysis of cultural products in general.
Anyway, there is another approach that is also valuable IMO.
That is, we understand any cultural work as fashioned from the author's internal worldview, which is itself formed from dynamic interaction with the world. So we can, for lack of a better word, interrogate an author's standpoint in their social world via their work.
The benefit of this derives from the specific characteristics of artistic products, which is that they have the capacity (and the permission) to convey a worldview in a way that no other secular product can. I think this, indeed, is one of the central points of the historical critique of art, which argues that art is invested with many of the functions of religious expression in secular capitalist society.
So, if an artistic product can express its creator's worldview, this is useful for us if we think a couple of things:
1) The artist is involved in a social system
2) Their worldview will be formed from their interaction with this system (this interaction needs further investigation, to dispel the stifling ambiguity).
If we believe these things, then the utility of an artistic product is in its capacity to convey the artist's worldview, its relation to their concrete standpoint, and hence something of their world.
The benefit is that we can hence understand radically different (whether distant in time, space, class, etc.) standpoints in otherwise impossible detail & unity. By engaging with many particular visions, we can start to construct something of a general vision. From the particular to the general, this, for me, is the movement of realism.