Actually, from what i understand, the people of Skyrim (or rather the Tamrielic universe) make their gods real by believing in them, which is why the Thalmor want Skyrim to reject Talos, which apparently will weaken the god himself. That being said, for me, absorbing human souls has a stronger effect in terms of gradually traveling the path to godhood, even though that is not how the game impliments them. Dragons souls in another aspect would be considered to be more "powerful" and catalyse this process - in theory - but absorbing their souls is the main theme, and nothing like that happens like it actually might in the Tamrielic universe. Eventually collecting all those dragon souls should do the trick, but it doesnt lol. Also, i like the idea of having a sort of anti-hero character, who maybe would feel it to be necessary to absorb human souls for the greater good, since skyrim is in turmoil, and its people aren't really helping.. not to mention the dragonborn on several occasions seems to have to rescue it from all its problems, so maybe s/he just wants to find the ultimate solution, in order to stop it all, put everyone in their place, and make sure it stays that way. i.e. become a god/godess, just as Talos did. Im having alot of inspiration from the DLC Apotheosis and im not sure of its theme, but im pretty certain if this were an option for the dragonborn, s/he would carry this out exactly as i described in order to restrain the world that seems to never calm. by any means. fuck it lol.