Tyler Cowen offers a quote on innocence by Casanova:

The girl’s quick mind, unrefined by study, sought to have the advantage of being considered pure and airless; it was conscious of this, and it made use of this consciousness to further its ends; but such a mind had given me too strong an impression of its cleverness.

That is from History of My Life. Is that why human self-deception has evolved?  If we don’t know our own artifices, we can more successfully conceal them from others.

Yes, we self-deceive to gain advantages from innocence.