Not sure if this also applies to Serie A, but in some leagues, the winner is decided based on their second-half performance of the season. I remember that Man City usually stumbles in their first few games over the last few years (including when they won so many trophies). I think the competition was even tighter last season, right up until the last few games for Serie A, too? So yeah, I'd also think twice before making a bold prediction on who will win the league this early in the season.
Yes, it's something that can't be predicted. There are teams that have won by a significant margin, like Inter who won 5-0 against Torino, but it's very difficult to understand who could win the championship. There are certainly teams that are already imposing themselves, but it's really difficult to understand on the first day. I wouldn't make any predictions.