Now that I think about it, the on ramp could be the original Jess, but I think the body in the trunk is actually the kid. If you recall, in the beginning, when she is carrying him outside, she’s telling him she has cleaned up all the paint on the floor. I think what happened is that she couldn’t console him and in the anger she hits him and he dies. She puts him in the trunk and shows up dazed at the docks. Tells them he is at school. That’s when the time loop starts. That is why when she gets back to the house, she is so easy to kill her self. She kills her because she killed her son in her anger. She tries to save her son from death, but he dies anyway. So she enters the loop again to try saving him again.