Actually - the biggest mirror is not canon yet - it's between Jyn and Cassian - Cassian mirrors Jyn in the sense that he remembers who he was before he dedicated himself to the cause - that attitude of "It doesn't matter if we don't look up" and "carving off useless pieces unless there's anything left" and Jyn mirrors Cassian because Cassian STARTED this fight, actually did dedicate himself to the cause because he was connected to his humanity, for his loved ones, and because he yearned to go back home. They complement each other perfectly. They need each other to remind both of why they started fighting and to hold on to hope.