In saying that literary works are about exactly what they seem to be, I am leaving open a few options.

(1) A work may be confused, a "problem play" so to speak, where there might be a serious discrepancy about two or more possibilities.

(2) A work might be so far removed in time that we no longer understand it. We have lost the references that make it intelligible. Maybe we don't have the actual philological wherewithal to decipher the text.

(3) There are poems I've read a hundred times that have obscure passages. We might not know how to construe particular phrases in Milton's sonnets, for example. Actually parsing them syntactically can be quite difficult.

etc...

In other words, there are literary enigmas to be resolved.

So from one point of view things are pretty much as they seem to be, and from the other point of view there is very little that is settled knowledge: we can still debate the "meanings" of even very canonical works. I myself vacillate between these two positions, and on any given day might find myself anywhere on the continuum.