Since Morrowind, they kinda retconned golems out. That used to be what atronachs were, before they went the much cooler route of having automaton-making being a lost art.
Flesh Atronachs? Those certainly aren't ordinary Daedra.
I'm no lore-knower by any means, but I still have no idea how dragon bone and dragon scale got into the laboratory of Serana's mom before they got split up.
Likely because when they split up was a very, very long time ago, pre-dating the empire, and thus the Dragon's being almost hunted to extinction, judging by some of Serana's dialogue. As such, Dragons would have been a much more common presence and their components available, if likely extremely rare.
Remember that Mirmulnir, the first dragon you fight, wasn't revived by Alduin but was simply in hiding until he heard that Alduin had returned. Naturally, he's kinda angry that the second group of mortals he fights happens to include the Last Dragonborn.
Not to mention that even Tiber Septim had at least one Dragon lieutenant (his other choice was being killed, I'm sure, and Tiber was also Dragonborn, so that's not very good).
Also related: I was kinda weirded out when I first met Serana and realized how
old she is. Like, come on, how're you speaking Cyrodiilic? I think it would have been much better if she came out and started speaking Ehlnofex. I mean, they had plenty of Dragon language worldbuilding in Skyrim, why not go whole-hog?