that's not right because:
humans and monster used to hate each other, most monster girls eat humans and only see them as food
and humans hunt the girls to sell their monster parts,(presumably rape the human parts as well)
the world used to be like in monster hunter world (the game)
(with the difference that all the monsters are sexy girls who try to murder and eat you

)
then this ominous evil being shows up and uses its/her demonic power
to unite the different monster girls in their hatred. that's when shit got real

and the angels had to join the war. to save humanity from extinction

it was a brutal war in which the population of entire nations got literary nuked by the most powerful monster girls
the goddess was also beaten up. and recovering in the celestial realm during the war

(or maybe she was just shocked at how brutally her creations slaughter each other

)
just ask the girls about the past, they got some dark/sad war stories to tell
sofia and lucille (the angel in the church) have most of the information.
also feng is a walking corpse. reanimated by her only friend kotone
if the queen hadn't decided it was enough and brought the girls to her island
we would have a standard jrpg...