Why does "so much depend" on that imagery?

William Carlos Williams’ "The Red Wheelbarrow" is a brief imagist poem describing the utilitarian value of the titular object.
The wheelbarrow is "glazed with rain/ water" and stands "beside the white/ chickens." In order to understand why so much depends on this image, one must analyze the purpose of a wheelbarrow. Wheelbarrows are used to transport bulky, heavy objects from one place to another, typically in construction projects, landscaping, or gardening. The wheelbarrow uses a one-wheel lever that allows a single person to transport the objects they need that would be impossible to move on his or her own. Therefore, the wheelbarrow is a tool that minimizes the strenuous demands of physical labor for the individual.
Referring to the poem, the wheelbarrow is a household tool that is likely used on a farm, hence the presence of white chickens. When the poem was published in the early 1920s, agrarian labor was still relatively common outside of urban areas. Thus, when Williams writes about the wheelbarrow, he is trying to communicate the necessity it plays in someone’s—and maybe even his or her family’s—survival. A wheelbarrow, because it helps someone achieve their labor, is responsible for someone’s livelihood. Ergo, human survival depends on the red wheelbarrow that Williams’ describes in his poem.