I might be able to help. I enjoy perusing used book stores for old photography books, you can find all kinds of great stuff there. I picked up a book called
Eyewitness, 150 Years of Photojournalism by Richard Lacayo and George Russell and published by Time.
They list the beginning period of photography as 1839-1880 and publish a
fascinating photograph taken in Paris in 1839. Exposure time took several minutes, so the picture, taken by Louis Jacques Mande Daguerre, showed a tree lined street mid-day, but no people or horse and buggys came out because they were all presumably moving. However one person did come out, that was a man that was getting his shoes shined, ie standing still!

They say that this is the first known photograph of a human being (he was the only
person visible in the picture, bottom left).
They also say that "photography was not the invention of a single person or moment. It arrived at the end of a long serioes of discoveries, summoned by a lifetime of chemists, artisans and tinkerers. All of them shared the intuition that light could leave a permanent imprint on a flat surface that had been spread with some combination of chemical substances. Their discoveries culminated in the work of two men. One was [the aforementioned]
Louis Jacques Mande Daguerre, a Paris stage designer and enterpreneur. The other was
William Henry Fox Talbot, and English squire".
Hopefully that helps as a start. I'm sure there's lots more information out there. Please share what you find, it's a really great subject!