Have you ever heard of a culture, modern or primitive, in the history of the planet that did not believe in the soul. And if you have I would have to believe that 99% of all cultures have believed in the soul.
Appeal to Popularity Fallacy.
Even if 100% of the world, every single person, believed in the soul (which, no they didn't, especially in ancient mesopotamian cultures), they can
still be wrong.
There is no evidence for the soul. There never has been.
If a million people believe a stupid thing, that doesn't make it smart. It makes it a stupid thing that a million people believe.
The egyptians believed that they had souls, though, an immutable life force. When they died, their spirits would become birds. Also, everyone that they didn't like had no souls.
So if you're going to appeal to popularity, then why not claim that no one but the Egyptians had souls? That's an entire empire right there.
Also, do you have any evidence that souls turn into birds when you die? I'd like to see
that. If not, then you're just picking and choosing amongst beliefs to try to support your preconceived notion that has nothing to do with reality.