You still haven't looked at the bigger picture...
If there is no risk involved with charging interest, how is there "risk" without charging interest??
All banks & governments lend money on the basis that it can be returned, with interest so lending without interest shouldn't matter since you only lend money in the first place if you know you'll get it back.
there is risk with getting your loan back. who is more likely to pay back $1 billion loan - Saudi Arabia or Pakistan ?
The interest rate charged reflects the risk and time value of money
Is money always paid back ? Individuals die. Companies go bankrupt. businesses fail. countries disappear. currencies are made obsolete. you should study the history of money
why is gold valuable ?