Way earlier than 5th century
This is not supposed to be a Safe Haven for pushing non-trinitarianism
Especially pushing it with non-factual claims about history and original languages
Your opinion isn't evidence.
As far as non Trinitarian doctrine, did you read what I wrote? According to the rules, in order to post here one has to adhere to the Nicene Creed. I do. I have been arguing just what the Nicene Creed says, there is one God the Father. The idea that there is a being called God who consists of three persons is NOT Nicene theology. It is found in the Athanasian Creed from around 450 AD.
Nicene Creed:
I believe in one God, the Father Almighty, Maker of heaven and earth, and of all things visible and invisible.
And in one Lord Jesus Christ, the only-begotten Son of God, begotten of the Father before all worlds; God of God, Light of Light, very God of very God; begotten, not made, being of one substance with the Father, by whom all things were made.
Revised Nicene Creed 381 AD.
We believe in one God, the Father Almighty, Maker
of heaven and earth, and of all things visible and invisible.
And in one Lord Jesus Christ, the
only-begotten Son of God, begotten of the Father
before all worlds (æons), Light of Light, very God of very God, begotten, not made, being of one substance with the Father;
Athansasian Creed:
1. Whosoever will be saved, before all things it is necessary that he hold the catholic faith;
2. Which faith except every one do keep whole and undefiled, without doubt he shall perish everlastingly.
3.
And the catholic faith is this: That we worship one God in Trinity, and Trinity in Unity;
4. Neither confounding the persons nor dividing the substance.
5. For there is one person of the Father, another of the Son, and another of the Holy Spirit.
6.
But the Godhead of the Father, of the Son, and of the Holy Spirit is all one, the glory equal, the majesty coeternal.
As you can see the Athanasian Creed differs quite a bit from the Nicene Creed.