The hero of the Elder Scrolls adventures, as we know, typically appears in prison with seemingly no knowledge of his/her surroundings or the people that inhabit them. In a http://www.uesp.net/wiki/Oblivion:Escape_From_Prison, the hero of the Oblivion Crisis seems to appear in prison one day with no idea how he/she got there, who the hell this kindly http://en.wikipedia.org/wiki/Jean-luc_Picard is, or what he/she should do with him/herself. They have no possessions save the clothes on their back, no skills or increased attributes except for what their race allows them, and even no class to speak of! Their only advantage seems to be the ability to be in the right place in the right time and the opportunity for level growth and, especially, attribute potential beyond what any other citizen can ever hope to accomplish.
It seems to me that, barring the possible excuse of "prison atrophy" and a background the player is free to imagine, that the in-game world reason for this "character creation" may be that the http://www.uesp.net/wiki/Lore:Aedra deem it necessary to create a hero, and they need to do it quick. It's as if the gods look at the world and decide there is http://www.uesp.net/wiki/Oblivion:Glarthir worthy to save it from its current crisis. So, they make a person full of power and potential that can be unlocked in mere days, already in their young advlthood to late senior years. After they save the world (or province or continent, etc) they are free to live a life as they choose, perhaps a normal life besides having no childhood memories or experiences until they die to take their place in the hero's circle or what have you.
Does this seem a possible explanation to you?
Daedric Form
Though it's easy to tell that I'm a fan of the http://www.uesp.net/wiki/Lore:Hermaeus_Mora, please don't take this next possibility as too biased. The reason I've come up with this (and perhaps I'm not the first) is my time spent thinking on Hermaeus Mora, His nature and demeanor, and so forth.
I believe I have read thathttp://www.uesp.net/wiki/Lore:Daedric_Princes may assume any form they choose, and if I did not read this I'm unsure where the assumption came from, but assuming that this is the case, especially when one looks at the many varied looks of a Daedric Prince (from http://www.uesp.net/wiki/Lore:Molag_Bal to http://www.uesp.net/wiki/Lore:Azura to http://www.uesp.net/wiki/Lore:Mehrunes_Dagon to http://www.uesp.net/wiki/Lore:Clavicus_Vile), isn't it reasonable to assume that Daedric Princes might all have an original form?
Just as many of the mortal races have changed over the many thousands of years of recorded and spoken history, and indeed as some http://www.uesp.net/wiki/Lore:Trinimac#Trinimac have, and also since the daedra are http://www.uesp.net/wiki/Lore:Padomay#Padomay in origin, it is safe to assume, in my mind, that the forms we see the Daedric Princes take today are not necessarily the forms they have always had.
http://www.uesp.net/wiki/Lore:Mephala changes gender appearance to suit its audience's tastes, and http://www.uesp.net/wiki/Lore:Boethiah has been known to "take the form of" another deity at least on one occasion. And being such unfathomably powerful beings that came well before mortal kind, perhaps before the "human" form took shape, they probably have some sort of primordial look to the forms they originally took. Maybe somewhat shapeless, with random parts that would inspire future creatures?
My proposal is that though the Daedric Princes wear many masks, there is but one who is completely unconcerned with the physical and only with the mental, going so far as to retain His original shape either out of lack of interest for how He looks to mortals and immortals alike, or out of some kind of pride, or to send a message of the lack of importance He places on appearances. When we look upon Hermaeus Mora's "disturbing" form and listen to His guttural voice, then, I believe we are experiencing an http://theelderscrolls.info/images/artikel/oblivion/quest/daedra/mora/DAE_Mora_2.jpg just as he was created or appeared so many millenia ago. Before there is the concrete, there is the abstract. The mud, the clay from which other things, beings are created.
Is that one more on the money, or not? I value all opinions on these two ideas and would welcome any facts, conjectures, wild hunches or anything at all about the subject.