So, not sure if you've ever played RimWorld but there is a Protogen mod for it. However, the mod brings up a very interesting concept that, until now, I haven't really thought about.
Now, Protogen are the result of high technology, right? And assuming that these tribal Protogen didn't come about due to a decline in technology from sci-fi to Bronze/Iron Age due to some unspecified disaster, this implies proto-Protogen existed, that later developed the technology associated with their biology, and made them into "normal" Protogen.
Which raises the question of what these proto-Protogen looked like before they had a "semi-synthetic evolution"?