Dense (and probably OP) MC.
All races are definitely humans.
Parents travelling into the demon kingdom just to abandon their child, and for a crappy reason.
Princess being demon lord's daughter, yet she grows at the same rate as MC, aka same lifespan between demons and humans.
I mean, Author-kun, you could have just called them all humans from different nations at this point.
Also what's with those long/lame titles.
Ain't following this.