I think that the subject matter of Brooks' poem connects to her life. Brooks understood the reality of racial dynamics and how it impacts people in the modern condition from an early age. Seeing how race impacts youth as a student in an integrated high school, an all Black high school, and an all White high school, Brooks was able to draw upon this understanding and develop it in the poem. The idea of "We Real Cool" is to show a sense of what it means to belong to a group and yet be invisible to others both within it and outside of it. Consider Brooks' own understanding of the poem:
The WEs in ’We Real Cool’ are tiny, wispy weakly argumentative ’Kilroy-is-here’ announcements. The boys have no accented sense of themselves, yet they are aware of a semi-defined personal importance. Say the ’We’ softly.
In this, one sees how Brooks saw the lives of young, Black men of the time period. The desperate attempts at solidarity and identity in the face of brutal discrimination and hopelessness do nothing more than to blight them, erasing them from the view of social reality. In their "softness" is a sadness that Brooks knew all too well from her own life and the awakening of her own condition as a woman of color in a social setting that failed to properly understand what this means.