Board Thread:Questions and Answers/@comment-36914736-20191125052140/@comment-29325824-20191125081313

To be honest, even the novels (if you care about them) say that Shinigami (even Urahara of all people) are not sure if a Vasto Lorde is a single, dominant personality, or an amalgamation of several dominant personalities. It could even depend on the "individual" in question. If it's the former, I can believe the resulting Arrancar looks (mostly) like their original human self, yes.

Besides, if most Soul Society residents cannot remember their human lives anymore, I highly doubt very old Menos Hollows can.