Protogens/primagens aren't really considered anthro or feral because they only have the one form, just like sergals arn't really considered anthro since they don't have a feral from. I also believe with protogens one of the rules is to stay on model, I'm not sure if that applies to making them more human like but I know they can't be a hybrid, primagens are not included in that rule because they are closed species only.
There is also I guess it like a concept backstory to primagens that there were some sort of human/primgen creature but I don't know much about it, but you can see it in this art piece
www.furaffinity.net: [C] LOYALTY by Malice-Risu
The best place to see protogen/primagen art would be Malice-Risu on FA
Userpage of Malice-Risu -- Fur Affinity [dot] net she's the owner/creator of the species.
Also here is some of my bad art of references of my protogen if you're interested in seeing it