The origins of Artemis lie in Minoan religion, the pre-Hellenic culture that dwelt in Bronze Age Crete. The Minoan Artemis was not the goddess of classical mythology —the sister of Apollo—, but a primitive type of deity that became especially widespread in the Peloponnesos and among the Dorians.

This Artemis was the Mistress of Animals, the Goddess of Wild Nature, which has not been touched or altered by men. She roamed about mountains and woods, in shadowy groves and wet meadows, hunting and dancing together with her Nymphs of whom she was but the foremost and the leader, as can be argued from Homer’s Odyssey, where Nausicaa and her handmaidens are compared with Artemis and the Nymphs (Odyssey 102-109):“And even as Artemis, the archer, roves over the mountains, along the ridges of lofty Taÿgetus or Erymanthus, joying in the pursuit of boars and swift deers, and the wood nymphs, daughters of Zeus who bears the aegis, share her sport, and Leto is glad at heart; high above them all Artemis holds her head and brows, and easily may she be known, though all are beautiful: so amid her handmaids shone the unwed maiden.”
(transl. by A.T. Murray)
The Nymphs were young female creatures, neither goddesses nor women: they were not immortal, but enjoyed very long lives.

A Hesiodic fragment witnesses that they lived 9720 human generations (fr. 304 Merkelbach – West):A screaming crow lives for nine generations
of men who have reached puberty; a deer is four crows;
the raven grows old at three deer; then the phoenix
at nine ravens; and we at ten phoenixes,
we beautiful-haired Nymphs, daughters of aegis-holding Zeus
(transl. by Glenn W. Most)Among the Nymphs were also the Naiads, nymphs of the springs:
and the Dryads, spirits of the trees, who dwelt inside the oaks:

The Dryads (from Greek drys, “oak”, but in the beginning “tree”) were thought to live so long as the life of the oaks where they dwelt (Homeric Hymn to Aphrodite, lines 264-272):But at their birth pines or high-topped oaks spring up with them upon the fruitful earth, beautiful, flourishing trees, towering high upon the lofty mountains (and men call them holy places of the immortals, and never mortal lops them with the axe); but when the fate of death is near at hand, first those lovely trees wither where they stand and they bark shrivels away about them, and the twigs fall down, and at last the life of the Nymph and of the tree leave the light of the sun together.
(trans. H.G. Evelyn-White)

The early Artemis was a Goddess of Fertility, not of agrarian fertility but of humans and wild animals, helping and assisting females in childbirth: she was the Protectress of Girlhood.
From those common data start two lines of development, which lead on one hand to the Great Mountain Mother of Western Anatolia, who roams the mountains accompanied by her lions,
and on the other hand, to the virgin huntress of Classical Greece:The former was associated to a Goddess of Fertility and to the renewal of nature, while the latter, as the Goddess of Virgin Nature not touched by men, became a severe virgin not tolerating any male partner. Among Greek goddesses, Artemis is the one whose assimilation to the Moon was deeper. Such deep assimilation is likely to be ought to her nature of archer, in the same way that happened to the sun god Apollo, with the arrows as a clear token of the sun or moon-rays.Although the clear evidence of such assimilation is not earlier than Classical Age (Fifth Century B.C.E.), perhaps it already existed at the end of the Seventh Century B.C.E., as it can be argued from a fragment of Sappho (fr. 34 Page):The stars hide away their shining form around the lovely Moon when in all Her fullness She shines (over all) the Earth
(transl. by D.A. Campbell)

It’s almost certain that the poetess was speaking of a girl who outshone her companions in beauty. Now, since the most obvious comparison of this kind would be that of Artemis and the Nymphs, and its best known image was that of the Odyssey’s passage, it would be suggested that Sappho’s lines were a graceful allusion to Homer. Hence, it is possible that the charming comparison of the girl and the companions to the Moon and the stars infered another more obvious comparison to Artemis and the Nymphs.
Artemis’ assimilation to the Moon increased in Hellenistic times (from Third Century B.C.E.), being often confused with
the minor deity Selene —the Moon herself—, and with the Egyptian Isis, another Moon-deity.