It's good it was actually an older person with a kid avatar in a game, though I suppose not hugely older, considering she was still missing her mom so soon. Maybe middle school or early high school with a bit immature personality. A real eight years old child would be pretty much good for nothing on their own and would only depend on adults, so it could be troublesome in a fantasy setting as an MC. As a sidekick, sure, but not the MC.