Collective liberation comes from the idea that all oppression is rooted in the same systems, so therefore all liberation is interconnected. In other words, we are not free until all of us are free. 

For a deeper understanding of this stance, and why we include nonhuman animals in our vision of collective liberation, we highly recommend that you check out Racism as Zoological Witchcraft by Aph Ko.

Above are just a few examples of how all liberation is interconnected.