The answer as we will discuss later in the motors section, has to do with the fact that that power generation (ie. spinning electromagnets) often produces in sinusoidal waveforms, and our power distribution network predates the switching power supply and readily available diodes for rectification.
AC allows us to inexpensively convert between voltages using transformers (where we prefer long distance transmission to happen at higher voltages). It’s also safer for domestic applications. We also switch at relatively low frequencies to consider loss.
