Castlevania did exist before Kojima came along
Never said otherwise.
and I think you would be hard pressed to convince someone that has had no exposure to the games released after SOTN that her art defines castlevania.
you mean on the internet right? Cuz I personally know people that don't even play Castlevania & still recognize her art as "Castlevania," or if they see something else she drew (a lot of different stuff) they'd still think it was
Castlevania-related.
Her work may embody aspects of Castlevania
Obviously, most definately, glad you agree!
in some regards her work was the complete opposite of Castlevania’s early identity.
You refer to the Conans wearing loincloths? That style went out with the 80s, and many other series used similar "tough guy with muscles holding a weapon" imagery, it was all over the place. So it's not like that particular style was unique to CV or anything. It was excellent artwork, don't get me wrong (CV1 still has the best boxart in the series in my opinion), but the Conan-esque look had to go. Belmonts are vampire hunters, not barbarians. However if they ever make a game or 2 set in the 1100s-1300s, I wouldn't mind seeing artwork depicting ____ Belmont wearing a bearskin or a Tanooki suit

Since in those days, they must've been really roughin' it!

Just to further clarify, if we were talking comics and I were to say "Jim Lee DEFINES Batman," many would agree despite there being dozens of other artists that came before him. I'm not saying those artists sucked, it's that he's just that damned good, and there's a reason why his work is so coveted amongst fans and why he has attained a level of notoriety over his fellow [well-received] artists.
*waits for the tired "kojima draws effeminate girlymen" argument to ignite*