I wouldn't worry too much about the MtG distinction of shaman since that's a recent change to the game where they're trying to codify the colours and spellcasters for each of them. I think it's something like cleric (white), wizard (blue), druid (green), shaman (red), warlock (black), though I could be wrong on those exact distinctions. There used to be plenty of crossover but by making each colour's class somewhat distinct they can probably create cards that interact with them in some way.
As for the shaman subclass, it can fit into plenty of classes: sorcerer, druid, cleric (I actually created a shaman domain a while back), warlock, bard, could probably fit artificer in there somehow (I think the designers even brought that one up). It all depends on how you want the shaman to work.