Blotty....As far as sophistication, there were a spectrum of conceptions of God within Judaism. No doubt for the less educated, he was seen a simple powerful patron of war or farming. That is probably why the writer of the prologue of John played off that OT phrase about 'no one having seen/perceived God'. God was something they had not perceived. The Son was understood to have unfolded/revealed an up till then 'unseen' God.
As has been extensively shown, Jews such as Philo and others had developed a very complex and lofty conceptions of deity manifest through emanations such as 'angels' and the 'Word', much akin to the writer of John's.
No, just as Kaleb said, the texts themselves do not explicit a Trinity doctrine but nor do they only describe a God that children could comprehend.