Interest rates match business activity to savings.

If I want to start some new business venture, I will compare what it costs me to borrow the money with what I expect to make from the venture. If I make more than the interest cost, I'll pursue the venture. Even if I already have the money, I could lend it out for roughly the same interest rate so I make (almost) the same comparison.

When interest rates go up, this tends to pull more money into savings (and thus away from consumption, freeing real resources). When interest rates go down, there's less reward for saving and consumption becomes relatively more attractive.

In a properly functioning free market, interest rates match non-consumption (savings) with business activity. "Money" in this process is a coordination mechanism for real resources. By delaying consumption (saving) I make real resources (concrete and steel, etc) available for business use.

When the central bank intervenes to suppress interest rates (perhaps by permitting fraudulent activity by commercial banks, perhaps by directly extending credit from the central bank), this increases the attractiveness of business activity (because the alternative is less attractive) and increases the attractiveness of consumption (because the alternative is less attractive). Thus real resources are withdrawn from business availability (and into consumption) just as demand increases. This is inflationary and disruptive.

Note that this happens even if the bank lending is only for productive business ventures. While lending for consumption is an important phenomenon, the shift towards consumption I am describing is the consequence of lower interest rates and lower incentive to save, not necessarily low cost for personal borrowing.