Parts of the TLM are ~ 1,600 years old.
[usual pedantic post]
Let’s see, in the Ordinary of the Mass:
The prayer ‘Aufer a nobis’, though it was not used in the same context as it is in the TLM.
At the Offertory, the prayer ‘Deus qui humanae’ though again it was not used in the same context, and was originally there for, I think, Christmas.
Parts of the Canon. Canon fully in place by the 6th century with variations in saints names and not all the parts said at every Mass.
And of course, the Sanctus and Preface (some Prefaces closely resemble or are practically identical to early ones particularly in the Gregorian Sacramentary, though of course, the earlier Gelasian and Leonine books contain an abundance of prefaces ).
Gloria (though it was only at Christmas in modified form, then later at Easter, then later only by Bishops for Sundays and only between the 9th-11th century by priests at most times as it is now)
From the time of St. Gregory the Great additionally:
The Kyrie (though again slightly different at times usually as part of a litany)
From the 8th century, the Agnus Dei though not in similar form as today.
Of course things like the Epistle and Gospel were there but the prayers connected with them are of later date. Same thing goes wiht the fraction and the Kiss of Peace, etc. The Collects, Secret and Postcommunion were also there though of course, not all with the same texts as in the TLM.
Have I missed something out? [/usual pedantic post]
Would it be too argumentative to note that except for the first point and part of the second and part of the embolism of the ‘Our Father’, all these are present in the ‘Novus Ordo’ also?