You still have not explained why the business cycle has existed as along as business has existed.
You can sit there and quote lectures all day, but the historical record still disagrees with you.
Because there are very few instances of historical record where 100% reserve banking has been enforced.
I'm not familiar with a period of US history where there was widespread 100% reserve banking in place.
Since anything other than 100% reserve banking will cause business cycles, it should be obvious why the historical record shows business cycles going back as far as we can see in the economic data.