Saying it might be on a continuum just obfuscates things. What do you mean exactly?

If there is no sense of self or personal identity, how is that different than a block of wood or a computer? That there might be "mental" functions performed doesn't give it subjectivity if there is no subject performing them. And if there is no persistent reflective self there is no subject. You could call instincts or trained behaviors mental, activities of a kind of mind if you wanted to. But if it's not self aware it's not a moral subject.