If, on the other hand, the various texts are not understood to have has single divine source, and were instead written to subtly reference political, economic and sociological realities under the veil of theology, it makes sense that each perspective be isolated from the other and placed in those various contexts.
Does that follow? Are there other options?
I personally think that the truth is a mixture of both. The single divine source of scripture is of such a nature that "it" ("he") interacts with history, politics, economics and sociology. That's just my particularly incarnational way of construing the divine referent. The hermeneutical result is that both sides of the coin need to be taken into account. Each text was written in a particular context and this context is important to catching an important element of the text's meaning. However, the divine source that evoked the historical witness ensures that the proclamation of once upon a time is caught up within an unfolding drama, such that later generations would respond to the original witness from the perspective of a broader understanding of the divine source, incorporating this understanding into the literary shape of the text itself. Whether Moses wrote the Pentateuch or JEPD, the various voices have been combined into a literary whole, the shape of which guarantees a proper glimpsing of what the various stages only glimpsed at before (a what these stages were ultimately truly interested in).
In short, making the hermeneutical decision to read the final form of the text only makes sense if one subscribes to this particular understanding of the divine referent. Knowledge of referent determines hermeneutic.