My understanding was that the writing started to keep tabs on the taxes. It was code that was kept "secret" for whatever purpose. The earliest texts were little more then Bob owes 20 sheep. Of course as is the case with anything, once the concept is out there others think of it too.
It is thought that the Noah myth was actually sumerian in orgin and it was a flood of the Tigri and Euphrates. Of course there are other hypothosies. http://en.wikipedia.org/wiki/Holocene_Impact_Working_Group
The use of money however was not new. That concept has existed for a very long time before. The actual coinage though was first exemplifed by the sumerians.
what also needs to be pointed out, is that the examples we have of art and writing and such exist because there was a concentration of them. Which implies a diversified economy, political stability, and a decently large population. Thus we generally see these items from the height of the civiliazation. Additionally, the desert environment helps.
On of the difficulties of reseaching Norse civilization is they made their settlements from wood, which decays in wet environments like the Baltic. Similar is true for other celtic tribes, native americans, etc. The whole reason we know some of what happened to the Anazazi Indians is because they lived in Arizona.
Anyway, just some thoughts.