Lower interest rates will increase investment, and lower interest rates will also reduce savings. So why is investment equal to savings?

This has troubled me for a long time, in fact, because the foundation of economics is not solid. I can assure you that many people who study economics don't understand the meaning of investment and savings.

It is suggested that two sectors of Gao Hongye's macroeconomics, simple national economy, I=S, the difference between actual investment and planned investment (investment under balanced conditions) and the concept of inventory investment are also very important, but interest rates are not considered in AE-NI model.

If you consider the interest rate, you can directly look at the simple (classic) interest rate determination theory. What determines the equilibrium interest rate is the intersection of the investment interest rate curve (downward slope) and the savings interest rate curve (upward slope), so your statement is not contradictory.