The reason there are no records before the bronze age is because people hadn't got into religion much before.
Had the situation continued without religion it is a reasonable assumption that nobody would yet know there had been a Bronze Age or that it was 3000 years ago.
As for informing the A2K viewers of those two amazing facts on this machine you can absolutely forget it mate. You can probably forget reaching the ripe old age you have done as well and having such long experience to be able to claim a God who you don't believe exists.
Are we supposed to define human life using new-fangled instruments?
I believe humans are prone to believe in gods; it's in our genes.
Which tribes might those be? Even Native Americans believed in gods. I think many early human history had idols of one kind or another, and the more developed cultures had many gods.
The Pirahã tribe in Brazil have no god or creation story. In fact their language doesn't allow for things that are not actively observable.
The Pirahã have no concept of a supreme spirit or god and they lost interest in Jesus when they discovered that Everett had never seen him. They require evidence for every claim made. They aren't interested in things if they don't know the history behind them, if they haven't seen it done. However, they do believe in spirits that can sometimes take on the shape of things in the environment. These spirits can be jaguars, trees, or other visible, tangible things including people. Everett reported one incident where the Pirahã said that “Xigagaí, one of the beings that lives above the clouds, was standing on a beach yelling at us, telling us that he would kill us if we go into the jungle.” Everett and his daughter could see nothing and yet the Pirahã insisted that Xigagaí was still on the beach.