We all know that Granite is one big "fuck you," but there is something in Vessel's voice towards the end of the song that changes it a little for me.
The "I was more than just a body in your passenger seat" at the start is a statement. It's a definite. There's nothing behind it beyond pure fact— tinged with anger, yes, but not uncontrollable rage. It is an "I am here and I am a person."
The last "I was more than just a body in your passenger seat" at the end turns pleading (the entire verse has a pleading note to it, to be honest). It's gone from "I was more" to "please, recognise me as more, recognise me as more than a body, I am begging you." There's a desperation for identity, for autonomy, for acknowledgement of his personhood. The "but I am" yelled at the very end really punches this into place.
It turns a "fuck you, I am a person" into "I am a person, please see that," walking the line between powerful and tragic.