As I understand it, the Trinity is a fairly thought out model harmonizing the different ideas on the human/divine nature of the Jesus/Christ figure and monotheism.
If the Nazoreans or Ebionites were truer to the teachings of the earliest "christian" movement, then Jesus wasn't God. But the waters were likely muddied by Saul/Paul throwing his ideas into the mix (which show a strong similarity to some gnostic ones). But the gnostic movement wasn't homogenous and there were different ideas on how many emanated divine beings there were in the pleroma or Godhead. You could think of Jesus as an emanation of God, but then it looks like gnostic christians also believed that in a sense they were too. That their true natures were divine and that they'd return to the pleroma. The broad camps even wrote rebuttals against each others views. I don't think the Trinity was by any means something that was explicitly taught at the earliest stages if the movement. Just like today you can find people eager to deify some gurus, you had believers who deified Jesus.