No, I have no brilliant or even non-brilliant insight about 3rd vs. 1st person in memories, though what you were implying definitely seemed logical.
I will now recap some of my first memories. And Ben, I wasn't that little when summer wars happen. I have a fairly chronological sense of many summer war memories (when you and Joey let Anne and me catch you, but we didn't have a prison 'cause we'd never actually managed it, and you told us to just put you in the Jones' garage, and you prooomised you'd stay, but we came back and you left?) among many others.
1. I have some extremely fabricated early memories. Let's start with the first. Me almost driving the van into the lake. I see myself crawling into the drivers seat, and Mom and Dad running out of the house with a look of terror on their face, and then crashing into the tree after I leaned the gear thing all the way into drive out of reverse. Must be totally false.
2. Also fabricated: My 1st birthday party, at the shack, sitting in that seat that clipped onto the oak table, with a blizzard outside, while Mom got me a bottle.
3. I think this is real. Mom let me pack my little pink plastic Barbie suitcase to move from the shack into the farmhouse. She was just letting me have fun, since she was actually taking care of everything, but it was great, and what I remember is walking down that sloping front lawn, holding that plastic Barbie suitcase, and feeling oh so important and grown-up. Age: I don't know, but I was walking.
4. Possible real memory: Talking to Uncle Dale while he was in the garage at his former house on Courtright. Was I even alive when they were living there? Considering I didn't know 'til I was 15 or so that Dale was on his 2nd wife, this is probably fake.
5. As Ben mentioned, the strength of the 1st person-ness of this memory makes me think it's real. In 1 and 2 it was pure third person. I was sitting in that old blue van in my car seat. It was parked outside a barn (or polebarn?) that had tall grass growing along the side. Everyone piled out to get stuff. I was the only one in a car seat, and I remember watching everyone get out, while I sat buckled in, wondering where everyone was.
I think #3 and #5 are my most legit. First memories are so weird the way they're so fuzzy, but you remember certain details so clearly.
I can only guess about my ages in these. Two or three? Who knows.