The Tanakh already existed. Neither does one need to possess all of the canonical scriptures in order to recognize Holy Writ as being more than human literature or oral traditions.
While all of the books weren't individually enumerated, categories of books were recognized as
theopnustos/God-breathed: the Tanakh, the Gospels, and apostolic Epistles were all used for public reading.
There is a highly illogical double standard at play here. People who believe in Sola Ekklesia expect some sort of exhaustive support for Sola Scriptura in the 1st century Church in spite of it not existing either in favor of their ideas.
I've brought up the general debate over the canon and why Jerome ended up labeling certain books as apocryphal in the Vulgate. Also I have demonstrated examples of bishops whose teachings we all consider soundly Orthodox who propagated plainly mistaken traditions (e.g. Irenaeus thinking the Lord was crucified at an advanced age), casting very reasonable doubt on the ability of the Church in the first place to preserve extra-biblical traditions in spite of cultural syncretism. As of yet I've received answers on neither account.
Can our interlocutors here, who have such high standards for Sola Scriptura to meet,
show us the continuity of thought they are claiming?
Scripture teaches it's sufficiency (2 Timothy 3:14-17) and that we are to test spirits and right doctrine by it's acknowledgement of the Son, it's relationship with the Holy Spirit, and finally harmony with Scripture (Psalms 19:7, 1 John 4:1-6, 1 Thessalonians 5:21, 2 Peter 1:20-21, 2 Peter 3:15-16, Psalms 12:6, and Colossians 1:23-29). The Scriptures appear to be
quite outspoken about their value.
Jesus points to three primary witnesses: His Father, His works, and Messianic prophecies. Where are the Father and where are Jesus' miracles? Well, we can't perceive those but we can read the prophets.
The Masoretic text didn't exist in the 1st century. At that time they kept scrolls of the OT in Paleo-Hebrew, which had different alphabetical symbols than Masoretic script and no vowel symbols. People make a mountain out of a molehill with the fact that in NT times there was the Septuagint, a proto-Masoretic text, and a proto-Peshitta (Syriac version of the OT) text in circulation because the text differences weren't a fraction as prevalent and frequent as folks tend to presume.
The whole idea of Reformers having actually taught
Sola instead of
Prima is unrepresentative and an anachronism, as it is a hyperbole of
Sola Scriptura.
Sola Scriptura as conceptually used by the very people who came up with the five
Solas did not view Scripture alone as profitable literature. It was strictly considered sufficient in the sense of 2 Timothy 3:14-17.
A source being sufficient doesn't make it comprehensive. God being an infinite being, any comprehensive account of Him is impossible in the first place.
The NT displays several examples of preexisting creedal formulas and liturgical texts. See 1 Corinthians 15:3-7, 1 Timothy 3:16, 1 Timothy 2:5-6, 1 Corinthians 8:6, and Philippians 2:5-11.
The Nicene Creed itself was closely adapted from the
Rule of Faith presented by Irenaeus in
Against Heresies. It can be seen here in
chapter 10. He had pretty much just finished establishing all of it in the Scriptures, resoundingly refuting Gnosticism and Marcionism almost solely through recourse to the Scriptures. He presents the
Rule of Faith in the formula of a creed, directly implying it was in liturgical use already, as liturgical use was the standard memorization device for all such material.