Polymorph vs. Resurrection: Um, no. In this setting there is a clear afterlife where the soul goes. You couldn't bring a soul back from there because the spell only transmutes the object/subject who is present, NOT adding any additional features such as a non-present soul. Were there no souls, it could be argued; but we have clear evidence for the existence of an afterlife (potentially many afterlives).
In theory you could transform the physical remnants into something that is technically alive; but it would be a magical construct of some sort, or a new entity composed of the same matter. It would not be the original person, whose essence had gone elsewhere.
Killing: Nope. You could make them an inanimate object, like a corpse, but the soul would still be present. This is the same as if you changed them into a chair. You could then destroy said object or corpse, but that would not be part of the spell. A powerful enough dispel effect could bring above-mentioned polymorphed "corpse-object" back to their original form, which would technically be an alive person. While similar in effect, this is not a resurrection.