Unified ideologies of factions in Heroes 1-5.

It’s no secret that many can’t imagine Heroes without such traditional factions as humans (Heroes 1-5), necromancers (Heroes 2-5), and barbarians (Heroes 1-5). But have you ever thought about whether these factions represent a continuous unity? Do they have any common ideology or concept? After all, the necromancers of Heroes 2 and the necromancers of Heroes 5 are quite different in terms of their origins. I propose that in this thread we discuss whether the ideologies of the factions are continuous and whether they exist at all.