If guts is pure chaos and grithith  is pure order but theres always a inbetween in all spiritual beliefs for this and i think that child might be it thats why we see baby guts get compared to the demon baby and moonlight child is with grithith

 thats why his relationship with grithith is just him being fully absorbed into him while his relationship with guts is born out of chaos and remains chaotic  the only true source of positivity for him is casca the woman who came  between both men (sorry for the phraseing) 

Even nietzchece said there are levels to ubermench 

Camel a person who is completly a victim to the world aeound them (grithith) lion a person who sees the injustice around them but struggles to do anything(guts)

And finally level 3 which he called child a person who is seen as childlike do to thier idealsim

 the moonlight child has 3 forms and i think once casca gets her hands on him he will enter a 3rd form where can see the dark and light side but chooses life instaed the ubermensxh also goes throupgh constant over comeing of himself and enviroment 

He also said ubermensch rejects soicety guts rejected death out of the chaous from his birth the moon light child was rejected by life and death 

Theres probably some esoteric moon and sun symbolsim but idc and yes the newest chapter makes guts special and gives more advantges than disavangtes 

Does the newest chapter make him true ubermesnch