The image of Issa with the molotov represents the key because it’s the retaliation of all the trauma not only put on him but everyone that lived in the projects. Issa is now the aggressor after being beaten for the entire movie.
The image of Salah offering up himself represents the key because it shows the power of peaceful protest. He disarms Chris and for the first time in the movie he’s unable to control a situation. Them being at eye level also emphasizes their equality.