““1700 years ago”? You have copies that can be dated accurately?”
Yes, nearly so. There are a number of fragments of texts of the Divine Liturgies of both +Basil and +John Chrysostomos from the late 5th / early 6th century. I suspect it is because they were and are so widely used. The older Liturgy of +James was never widespread but the oldest complete copy I think is from the 8th or 9th century.
The DLs of +Basil and John Chrysostomos both are derived from the West Syriac Liturgical tradition which was established at Antioch and thereabouts. The earliest versions of these liturgies extant are also from the 5th century.
It is quite literally true that if an ancestor of mine from, say, the year 500 showed up at my parish church for liturgy next Sunday, he’d know exactly what was going on.
At least quotations attributed to them.
“It is quite literally true that if an ancestor of mine from, say, the year 500 showed up at my parish church for liturgy next Sunday, he’d know exactly what was going on.”
But none of Jesus’ apostles would.