Well, do even silver coins have an actual value? They have the value people give them. They're more backed by the issuing government, it's economy and also their military(!!! - which is remarkable and dangerous) Silver itself has a value, like Gold, but it doesn't come anywhere near the value we give it.
Yes silver coins have an actual value, and yes this value is what people give them. The value of anything is what people give it. Food has value because people want it. The value people give silver is based on how much people all over the world are willing to pay for it.
Also, fiat is NOT backed by the issuing government and their military. Under ideal conditions it would be, but in reality they just print more and more and more money.
Silver isn't perfect, the value will fluctuate as demand and supply changes. But because a government cannot just print as much silver as they want (or create it electronically out of thin air as they do via central banking) it ends up being stabler (it shouldn't, it takes extreme idiocy to make fiat behave as poorly as it actually does)
Also, please note that I wasn't even advocating silver (although I do view it as a more solid form of currency then fiat), I was answering the hypothetical question of what people would use for cash if fiat paper money didn't exist. My answer was paper money that isn't fiat, or metal money