Definition of "artless"

And why should I here suppress the delight I received from this amiable creature, in remarking each artless look, each motion of pure undissembled nature, betrayed by his wanton eyes

1749, [John Cleland], “(Please specify the letter or volume)”, in Memoirs of a Woman of Pleasure [Fanny Hill], London: […] G. Fenton [i.e., Fenton and Ralph Griffiths] […]

I am convinced of her being an artless, amiable girl, with very good notions, very seriously good principles, and placing her happiness in the affections and utility of domestic life.

1815, Jane Austen, Emma, volume III, chapter 18

What passions our friendships were in those old days, how artless and void of doubt!

1848 November – 1850 December, William Makepeace Thackeray, chapter 19, in The History of Pendennis. […], volumes (please specify |volume=I or II), London: Bradbury and Evans, […], published 1849–1850