Hey there! I'm glad you enjoyed it, hah. There currently isn't a way to get humanity below 30% - I was going to implement a few smaller interactions that lose or gain you 5% or so, but ran out of time in the jam. So you didn't miss anything, don't worry.
It’s even cool that humanity remained in the character, even though he went through complete robotization, because humanity remained in him as a moral system and his past. This is more important than biological humanity. Utilikins also have humanity, as I learned from all three games (maybe I understood wrongly, I'm sorry), but they went about it in a different way.