Hi, twinc.
I’m nowhere close to a mastery of Sacred Scripture, but while God provided many, many prophets that guided us, they were all precursors and pathways to God’s ultimate plan, to make his Second Person (always and eternally present with the Father and Holy Spirit, but never revealed until the time of the New Testament record) incarnate, to live with us, teach directly to us, and even die for us.
Sacred Scripture of the Old Testament gives many prophetic hints that the Christ would come and why he would come. In Abraham’s obedient near-sacrifice of his son, God showed that no other sacrifices would ultimately appease him more than a sacrifice of something of great worth–your only child. But a mere human child (or adult) would not be acceptable (or just). Knowing that death would not affect Him but would eternally punish us, Christ’s incarnation created a way to kill death; while you could kill the human of Christ, the eternal might of the Second Person would not be easily vanquished. Since Christ was both human and divine, death became redefined, not as an end but as a beginning for the just dead to enter Heaven.
God made his Word present throughout the ages through objects or as a disembodied voice or a spiritual representation of a physical form (as angels did), but, to my knowledge, had not humbled Himself as much to become a man himself until the time of Christ Jesus.
And thank you for your question. It enlightened me by being able to explain something deeper and warming about the gift of God, not just to you but to myself, in this time of Advent.