And I don't think interest is a problem, it is just a natural thing
No it's not. When you create the money for the principal you don't create money to cover the interest. Those money do not exist and the only way for them to come into existence is for someone to take another loan to pay for your interest. But then what about the principal on that loan ... and the interest on that loan? And so on.
Let's discuss this with a simple example
On an island with only 2 people and one market:
Each day, A capture 2 fish and sell to market for 2$, he use that 2$ to buy 1 basket of fruits and 1 fish
B pickup 2 basket of fruits and sell to market for 2$, he use that 2$ to buy 1 basket of fruits and 1 fish
As long as they are doing this everyday, the total amount of money supply is constant, 4$ at maximum, and they are existing money
They can also take 0-intrest-loan to achieve this: A take 2$ loan, buy one fish and 1 basket of fruits for today's consumption, after one day's work, he capture 2 fish, sell them and return the loan, the second day, same thing happens...
If their productivity increased, A will capture 3 fish and B will pick up 3 basket of fruits every day, but they still consume 1 fish and 1 basket of fruits, then there will be stock of goods (1 extra fish and 1 extra basket of fruits), and there will be extra money supply, 6$ total for each day, and each day there are 2$ go into A and B's saving
Since the island does not have any way to store the fish and fruits more than one day, those goods have to be consumed. If A and B took loan to make the work possible, after A and B paied back the loan, they need to pay 1$ interest to the bank, thus bank get the interest, bought those extra fish and fruits from market and consumed them
So, the interest appears only when the productivity increased and there are extra products in the society. If the productivity stayed the same, there will not be enough goods to sell to market and get the money to pay back the interest, so bank's interest rate should be 0 correspondingly
Positive interest means continuously improved productivity in society as a whole, this has been the case for hundreds of years, and I think there is still room for more and more productivity increase, since people need to improve the quality of life all the time
This is a simplified model, market get loans from bank to facilitate the trade (adding money into circulation), they also need to pay back the interest, so the sell price from market will include these interest and the consumption of market itself, but do not change the way it works
From this point of view, banks, market etc all benefit from an increase in productivity, they just like some kind of middle man, take a small bite in the whole trading process, but since people are dependant on the service they provide, their charge basically get accepted