Remathilis
Legend
I've seen the term used in two different contexts that are at odds with one another.What does 'inherently evil' even mean? I don't think it is really a coherent concept to begin with.
Meaning one is that though some circumstance of their origin, they are born evil and that cannot be changed except in extreme circumstances. A goblin is born evil and the only choice he has is how he plans to act out his evil urges. This is the Always Evil argument. Evil is Nature.
The second meaning is that creatures born in an evil society will reflect the evil society they come from and the vast majority will align with that alignment. A goblin born in a goblin tribe will most likely be Evil, but one born in an elf society could be Chaotic Good. Evil thus is the result of the evil society they come from, and while you could theoretically deprogram them to turn from evil, the for the vast majority it would be impossible at best (think how hard it is to talk someone into changing political ideology and you get an idea how hard it would be). In this case Evil is Nurture.
The two meanings can co-exist (demons as nature, goblins as nurture) but things get dicey when they are conflated (as 5e did in places) and recently the two meanings are being challenged by a "new" one: Evil is Choice where nobody is born evil and society doesn't make someone evil, evil is a choice made consciously or unconsciously. So even a drow born of a Noble House in Mezzobarazan is equally capable (if not likely) to be good or evil as a human cobbler in Silverymoon.
Evil is nature, evil is nurture, evil is choice. Those are the three models and one of them isn't compatible with it's others.