In Joseph Conrad's "Heart of Darkness," the narrative often paints a stark picture of the environment and the shadows it harbors. The imagery described as "dark human shapes" suggests figures that are elusive and ambiguous, lurking in the shadows of the forest. This portrayal creates a sense of foreboding and mystery, adding to the novel's exploration of humanity's darker aspects.

The presence of these indistinct figures emphasizes the themes of isolation and the unknown inherent in the story. As the protagonist journeys through the murky depths of the jungle, the dark shapes symbolize the moral and existential challenges he faces, blurring the lines between civilization and savagery. This vivid description invites the reader to ponder the deeper implications of what lies within the darkness, both in the jungle and within humanity itself.