I came out from the Father (εξηλθον εκ του πατρος). Definite act (aorist), the Incarnation, with repetition of εκ (out of), while in verse John 16:27 we have παρα του πατρος εξηλθον) with no practical distinction between εκ and παρα in resultant idea.

Am come (εληλυθα). Perfect active indicative of ερχομα, as in John 18:37. The Incarnation is now a permanent fact, once only a blessed hope (John 11:27). His leaving the world and going to the Father does not set aside the fact of the Incarnation. Both αφιημ (I leave) and πορευομα (I go) are futuristic present indicatives.