The Dark Arts
If you want to throw in Polis, it is descended from pele meaning citadel or highplace central to the settlement (sel). Polis is a different word with its own meanings. But back before the appearance of e, i, w, y, the form was ku so before settlements, it was along the lines of nkuku-polkus: pol meaning to touch/shake, kus being a vessel containing things of a sacred nature so necropolis before settlement was a portable container you took with you. In igbo (nigerian) okpukpu is bones and I would surmise necropolis in its pre settlement form of nkuku-polkus is a container of ancestral bones that are touched/shaken. And taken with you as you travel. So the necromancer is initially some family member responsible for/trusted with ancestors remains.
The nek used is the same nek (protoindoeuropean) in corpse and nectar (of the gods). So the later Necromancer is searching for immortality and healing magic. Necromancers are not just digging up corpses and animating them. Necromancers are searching for immortality and they know the gods drink of it. Philosophically they might think the only thing gods drink are the lives of mortals through war, hecatomb (ritual mass sacrifice), pyramid building. Others might think the drink is some obscure fruit distilled down to its seed oils or juices. Honey is something of an antibiotic.
The necromancer lives in a world where enemies are contaminating artowheads with the plagues and bacterium of corpses and the sick (lepers). Knowledge of undetectable or incurable poisons is passed through the tribe elders. Something as simple as a termite mound can contain material which when powdered is a fine glass that will kill the victim slowly from the inside when blown in their face while they sleep. This is a brutal world... before and after the first human settlements. Necromancy is about medicines and poisons, healing knowledge, care for ancestral remains. This means you can have necromancers of any alignment and culture. A portable jar necropolis or a city of the dead.
The BX Necromancer
Access to both cleric and magicuser spells, though animate dead seems a chaotic act and thus the necromancer would be your cleric, and magicusers would be outcast necromancers. Because your cleric gets his or her spells by worshiping ancestors, something as simple as a reversed bless spell (desecrate) could eliminate a rival clan's necromancy by desecrating the bones of their ancestors. The world is a nasty place with little respect for the bones of others.
The Necromancer might be initially a cleric, but at a certain point a magicuser capable of animating dead to send the walking dead out for revenge on those who desecrated the family ancestors and took their cleric necromantic abilities.