The first four lines of "Caged Bird" focus on the life of a "free bird"—that is, one that doesn't live in a cage. The free bird is able to "leap / on the back of the wind" and simply float "downstream" without a destination in mind, continuing "till the current ends." These actions demonstrate its easy-going, carefree lifestyle.
The first stanza as a whole also introduces the free-flowing nature of the poem, which lacks a concrete rhyme scheme. This technique reflects the lack of restrictions faced by the free bird. At the same time, the combined use of assonance and consonance allows sounds to flow into one another, further contributing to this bird's sense of unrestricted ease. Note the many /b/, /w/, and /d/ sounds that dominate the stanza, in words like "bird," "back," "wind," "wing," "dips," and "dares."
This free bird is not only able to go wherever it pleases, but its sense of freedom also makes it feel powerful: it "dares to claim the sky." Here, the speaker complicates the previous graceful imagery of the bird by introducing this subtle notion that the free bird believes its freedom gives it permission to claim ownership over something that does not belong to it. This idea (which is repeated later in the poem) is likely an allusion to white colonialism and the American concept of Manifest Destiny, in which white European and American colonizers felt free to take control over land that belonged to others.
This allusion also begins to demonstrate that this poem is an extended metaphor for the oppression faced by marginalized communities (most specifically, by Black people in the United States). The experiences of the free bird are later juxtaposed against those of the caged bird, thus implying that the free bird is a symbol of the privileges afforded to a dominant social group.