So, this is a massive hear me out. But I'm actually of the personal belief that DnD classes can be interpreted two different ways. The first is the most obvious - In universe, the character would call themselves that as a role or job. You know. Ilphaer is calling herself a wizard. Beltrin is aware he's a Paladin.

Authorial answer?

But I also think a completely valid way to interpret DnD classes is as metatextual indicators of life experience. I don't think most rogues are calling themselves rogues, I think they're calling themselves like. spy's and thieves or pirates. Same with things like Fighters. People aren't calling themselves fighters they're calling themselves soldiers or knights. They're "fighters" in that is where their skillset sits, but their actual role sits closer to their subclass.

I think this is deeply subjective, and even within the same class be different. Some artificers would consider themselves that, but some might consider themselves to be wizards with a specialty in enchanting items. We as readers know that they're artificers based on our conception of what an artificer is and that they're being played/written as that, but their in-universe cultural concept might not be that.

Anyway, that's kind of where I place Sabdra at with her class. I don't think she considers herself to be a "Ranger" as an occupation (Though I do think that there are people who consider themselves to be rangers) I think she considers herself to be a Priestess and a Hunter and someone "Who see's the whole of Lolth's domain." And that what she does with that happens to fit the skill set of what we as an audience would understand as ranger.

So with that established.

In-character Logic.

Sabdra is a character with a lot of depersonalization inherent to the character. She doesn't see drow as a people on her level, she see's drow as another animal to hunt (with that hunt oscillating between something dignified and something inherently animalistic in nature)

On a more literal level, She's also just spent a lot of time traveling through the underdark and outside of drow society itself (and that part was a choice of hers to do). I would actually consider her both kind of a longer and an outsider, by any measurable standard. I actually considered her for druid for a bit there, because she has a bit of "Becoming the spider" in her as well, but the decision point for me was both in what her skill set relied on, and how I wanted to subvert her world view.

There's a mix of expectation and choice at play with her character. All textual evidence we've gotten is that being a chosen of Lolth is something that's inherently cannibalistic by nature. Lolth takes advantage of those she gives her favor to, and forces them to compete in the same way anyone else in their society would.