The Apocryphon of John, which pre-dated Irenaeus (though our oldest copy is from the 4th century), explains this circumstance.
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"And having created [...] everything, he organized according to the model of the first aeons which had come into being, so that he might create them like the indestructible ones. Not because he had seen the indestructible ones, but the power in him, which he had taken from his mother, produced in him the likeness of the cosmos. And when he saw the creation which surrounds him, and the multitude of the angels around him which had come forth from him, he said to them, 'I am a jealous God, and there is no other God beside me.' But by announcing this he indicated to the angels who attended him that there exists another God. For if there were no other one, of whom would he be jealous?
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"And the arrogant one took a power from his mother. For he was ignorant, thinking that there existed no other except his mother alone. And when he saw the multitude of the angels which he had created, then he exalted himself above them.
So this explains the thought behind why the Creator god of the Jews was thought to be arrogant and vengeful, etc.
As Barker explains in The Great Angel, this looks a lot like what we may expect from a religious group that descended from the original polytheistic Israelite traditions that preceded the Deuteronomistic Temple cult. This may describe the sentiments of a group that shared elements of the Jewish religious traditions, but did not accept the claim that Yahweh was the one and only god.
Now, it seems that many Gnostics attached to the idea that Jesus was sent from the higher god, who was the father of Yahweh (or in some cases just a separate power). But the question is, what evidence do we have that there were groups who believed that there was an unknown god higher than the Jewish god prior to the second century?
It seems that much of the "logic" of the Apocryphon of John stands on its own, even without Jesus. The teachings are attributed to Jesus in the Apocryphon of John, but they don't really have much to do with him. They could easily be earlier teachings that just got attributed to Jesus later. But the main thing is, do we have evidence of any of these types of teachings existing before, the middle of the first century?