The wounds of childhood trauma are relational wounds. They happened in the moments of neglect, abuse, self-centredness, carelessness and trauma.
This kind of trauma can create a distrust of all people, as you have learnt that people are not to be trusted, they are not safe.
As we use psychotherapeutic skills to increase our self-regulation, we are working alone to change the patterns of our childhood that are manifesting in our adult life. This is PART of the work.
In a two-person system, there are two bodies, two emotional systems, there is the interaction of two complete systems. With an attuned therapist it is possible to begin to heal relational trauma.