That's certainly what I think about at least the Jills. My interpretation so far is that there's a distinction between Jills and "normal" dragons, though. I may be wrong.
As for Aka being a dragon, that mythological basis is my supposition as well. I was thinking along the lines of the Ouroboros and what-have-you.
But Aka isn't just a serpent, he's a winged serpent, which I think carries some interesting symbolical connotations with regards to Lorkhan and their duality.
I'd be interested to see this.
This is where folks start creating confusion.
What is all this about "Winged Serpent"?
You were physically shown an
avatar of Aka at the end of Oblivion. Aka manifests as a dragon period.
Even if you were thinking about the Yokudan version of Lorkhan,
Sep, The word snake may refer to how they see Lorkhan's nature more than his being a serpent.
As far as we know, Lorkhan/Shor/Ysmir/Talos...all associated with dragons.