What was soul or intellect to The Greeks and Medievals and thinking substance to Descartes became consciousness for the first time with Locke. The change stuck, and we still use the same abstract noun. But do we still accept Locke’s reason for the term?
Locke is very clear that he wants consciousness to replace substance, the latter reality being, by his reckoning, unknowable. We do not have a self because we are substances of a certain sort (if this were so I couldn’t know I am a self) and so all self can consist in is the continuity of consciousness. Notice that Locke wants consciousness precisely as a continuous record of events – it is not so much awareness in a moment but a tale-of-the-tape that ensures that me-yesterday and me-now are the same person. Consciousness, and thus the person becomes a narrative record. Self ceases to be that which perseveres and becomes, with the idea of consciousness, the persevering itself.