Notice, too, the opening line of Luke:
1
Since many have undertaken to compile a narrative of the events that have been fulfilled among us,
2
just as those who were eyewitnesses from the beginning and ministers of the word have handed them down to us,
Many have undertaken. There were a bunch of Gospels written. It took the Church to decide which contained the closest to the Gospel that Jesus wants us to know.
And had the Holy Spirit simply "dictated" the Gospel to one of the Apostles, there would only need to be ONE.