What's the theme of "Our Wretchedness in Consequence of Slavery"from Appeal to the Coloured Citizens of the World by David Walker?

One of the most dominant themes of Walker's work is to
bring out the idea that enslavement is not something that happens only in America to
Black people.  Rather, it is a worldwide condition of those who are oppressed.  Walker
is wise enough to universalize the condition of enslavement to bring more people into
the struggle and allow them to fully grasp that there is a larger struggle for freedom
present.  Walker likens it to the Biblical condition of the Hebrews with Pharaoh.  This
helps to bring out the idea that the struggle that Black Americans are enduring with
slavery is one that all people who are oppressed have endured and do endure.  In this
light, bringing out the universality of "wretchedness" helps to bring out how
enslavement is a condition that can foster solidarity among those
oppressed.