None of which actually proves that she was the main target all along, even though she was taken. It is possible she was. But it isn't a certainty, by any means. You talk of other cases. There are other cases I have been aware of where a home invasion turned in to a sexual assault, even though that wasn't the original purpose of the home invasion. If that is what happened to Jayme, then it is possible they didn't kill here there - not out of a sense of wanting to spare her, but out of a need to not leave behind DNA. And if that is the case, they also wouldn't leave her somewhere where she could be easily found.
All I'm saying is that we shouldn't be so single-minded as to assume that just because Jayme was taken, then it automatically means she was the original intended target. She may have been. BUT - she may not have been.
But because the motive wasn't robbery and nothing but Jayme was taken, it stands to reason she was the target. Anything else is a HUGE stretch.