Only because there is conflicting information, I want to chime in and say yes, you can play as Alfred. It was one of my longest and favourite playthroughs, and I mentioned in briefly in the other thread (see below) I started my playthrough as Aethelred, he died childless in battle and Alfred took the reigns. Looking at the game now just to fact check, I find it interesting that Wessex now has a stronger start. I do not remember having the eastern duchies from the beginning. So much so I remember one of my immediate goals beyond defending against the Norsemen was to acquire the Duchy of Essex and move capitals. I think maybe Paradox had to make the changes because the Norse just steamroll otherwise. A stack of 25,000 troops is punishing, I want to say that it is possible to come out at the other end and roughly follow history.
Yeah, I took a bit longer to win against the Vikings in that game. I also distinctly remember the Dukes of Mercia having it in for me at every turn. Like some sort of ongoing family rivalry.
The Old Gods bookmark came first, then Charlemagne followed up with the earlier bookmark.