Do superficially encouraging statements within rejection letters for faculty job applications mean anything?
It could be both an honest statement or generic fluff. Unfortunately, there's no way for you to distinguish both, and to derive useful information here. (Maybe unless they comment on specific things they found impressive, but that doesn't seem to be the case.)
The more informative fact are the rejections themselves. A single rejection means hardly anything, but if you only received rejections, there would be some problem that you need to fix. The fact that you got some invitations is indeed a good sign.