Is it correct that the concept of God has been established by man himself and God Himself never came to tell us this?

All the evidence points to the simple fact that, yes: Is it correct that the concept of God has been established by man himself.

This explains why the thousands of gods claimed by thousands of varied groups all over the planet reflect the wants, needs, and desires of the people, rather than the other way around.

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With regard to "none on earth has seen God face to face",

In the Bible, just prior to claiming "No one can see the face of God, and Live", (Exodus 33:20)

there is a verse detailing how Moses and Aaron, Nadab and Abihu, and the seventy elders of Israel got to meet god, face to face, (Exodus 24:9)

and somehow, Christians do not see this as a contradiction (see: @OneDrop's answer, below).

No, God Himself has walked the earth. He created man. He walked with Him in the Garden.

Adam saw Him face to face.

Moses saw Him face to face.

Israel saw Him face to face.

Almighty God is a living man when He so chooses.

Iron age people didnt undestand the world. So they had to imagine up gods to create an understanding.

Bottom line..... There is no God or gods.

"Gods" are all Man-made political bullshit perpetuated by charlatans.

Case closed....

If only as far as you collect mattered, but as far as i can collect, God is God, so what are we gonna do now?

No. If you read the Bible you will learn the true story.

That would be self serving and bragging.