I believe the main character switches as the series goes on. At the beginning, it was mostly Shinn and the crew of the Minerva (see intro where Impulse was the intro suit). Now at the 3rd Op, we have Super Freedom in the intro. Now the emphasis will switch to the original characters of Gundam SEED and the Archangel. I wonder what suit will be in the 4th Op. By then, the main character might have switched once again either to another character or back to Shinn.

Kira > Shinn. No way Shinn can ever surpass Kira in piloting ability. Just think about it. Kira is restraining himself to only disabling his opponents. If Kira actually just shot them normally to kill, nothing would be able to beat him. Kira is just giving everyone a handicap, although he still ends up winning.