he earliest surviving physical fragments are generally from the second century; the earliest complete New Testament manuscripts are fourth-century codices.

There are many thousands of textual variants among the manuscripts, precisely because there are so many manuscripts and they were copied by hand. Scholars use those differences to reconstruct the earliest attainable text.

The manuscripts provide substantial evidence for what the New Testament texts said and how those texts were transmitted.

They don't independently “verify the facts” described in those texts.The manuscripts provide substantial evidence for what the New Testament texts said and how those texts were transmitted.

For example, manuscript evidence can establish that a passage about the resurrection was being transmitted very early. It cannot, by itself, establish that the resurrection actually occurred.

Therein is the point of faith.