Rather than avoid the complexities and nuances of being human and humanity as a whole, the speaker confronts inevitable, interconnected contradictions and embraces "multitudes" of expression. Conflict can bring resolution and new perspectives, death brings life, and internal conflict can lead to maturation.
In the context of a society, contradictions can represent change, growth, and challenges to dominant cultures and ideas. However, contradictions, particularly those that are unacknowledged or unaddressed, can also be like festering wounds that can destroy an individual or society. The concept of American democracy, for instance, holds vast contradictions in its representation of being a political system based on freedom while also having been founded on slavery and continuing to perpetuate human rights abuses through its carceral system (as one example).
When the first version of this poem was published in 1855, the US Civil War was brewing, workers in the North were suffering under the boot of industrialization, indigenous people of the Southeast had been displaced on a massive, genocidal scale two decades earlier, and Black people were still suffering the horrors of slavery. Certainly, the embrace of contradictions within this context could be seen as completely antithetical to the creation of a free, just society. How can all voices be heard if certain groups of people are being systemically silenced?
There are certainly massive distinctions between personal contradictions that can lead to growth and actionable contradictions on a societal level that result in systemic oppression. Perhaps the speaker is wrestling with how to build a democracy that embraces equality as well as contradictions without harming one another.