Children have all the time in the world. Adults are often impatient to "move on". This is one way in which they are mis-matched.
A child in distress, whether from physical injury or emotional upset, needs to be held. Sometimes the parent takes the initiative and embraces the child, sometimes the child clings to the parent.
Distress in a child is often overwhelming, exacerbated by the child's awareness that they have lost it. Lost self-control, self-possession.
It may take a child a long time to calm down and a good-enough parent will allow the child to feel that they are there for as long as it takes. It simply doesn't work to tell the child to pull itself together. The child knows it should and knows it can't. That's a large part of the distress.
It used to be standard in children's homes for staff simply to hold on tight to children in distress, acting out - throwing things, attacking people. I don't know if staff are still allowed to do that; I hope so.
Adults also need to be held and holding is one of the things lovers do for each other.
There are symbolic forms of holding. R.D.Laing somewhere gives an account of an analysis in which his patient / client sat silently. Laing responded in kind but got bored and tried to "move on". He began to think about other things; probably he began to fidget. The patient responded by saying, "Don't leave me". I doubt Laing was that surprised; nor would anyone be surprised who had read John Bowlby or D.W. Winnicott.
Children will let go when they have recovered. Made to let go too soon and they will cling. Rebuffed, they will eventually lose the capacity to be held and to hold.
Politicians, bankers and other important people are always telling us we should "move on". I do hope they don't say that to their children.