Rome's organizing in 325-ish was only a formality of cementing apostasies that were already widely held into doctrine. How many of the ECF's that you list above were Hebrew Christians? How many were Hellenizing-friendly Greeks? Your claim that they did not invent the concept of the Trinity is quite valid as it had already existed for over a thousand years.
Tertullian certainly wasn't nor were most all of the early church fathers. The Gnostics and disciples of Simon Magus were however followers of Greek philosophy. Irenaeus was a Trinitarian and at the same time wrote against the heresies of these Hellenizing Gnostics.
It does appear that the Ante-Nicene church was split between the trinitarian and the binitarian position, not knowing just exactly if the Holy Spirit was part of the Godhead with the Father and the Son --- but the unitarian position of the Arians led them into some outrageous heretical beliefs.
Your claim that they did not invent the concept of the Trinity is quite valid as it had already existed for over a thousand years.
No --- longer than that. They were the "us" there at creation and from eternity past.
Please explain who exactly the Father, the Son, and the Holy Spirit in the New Testament are.