Trauma and memory
Morrison shows trauma as something that doesn't stay in the past. It resurfaces, takes physical form, and acts on people who thought they had escaped it. Sethe's 'rememory' means the past can ambush anyone, even people who weren't there.
Motherhood under slavery
Slavery warps what motherhood can mean. Sethe's love for her children is total, but slavery made that love dangerous. Her decision in the woodshed is the extreme endpoint of a system that gave enslaved mothers no safe way to protect their children.
Identity and self-ownership
Every major character struggles to feel like they own themselves. Baby Suggs preaches self-love because it is the thing slavery most completely destroys. Paul D cannot access his own emotions. Sethe defines herself entirely through her children because she was never allowed to be a self.
The cost of survival
Surviving slavery leaves marks that don't heal cleanly. Paul D wanders for years. Sethe is shunned. Baby Suggs gives up. Morrison shows that freedom from legal enslavement does not mean freedom from what slavery did to a person's interior life.
Community and isolation
124 is cut off from Cincinnati because of what Sethe did, and that isolation makes her vulnerable. When the community returns, Beloved loses her grip. Morrison connects individual survival directly to collective support, and shows what happens when that support is withdrawn.