To get an electrical current to flow through metals, the power source has to fight against resistivity. The lower the level of resistivity, the more electrical conductivity a metal has. And since copper wire has a low level of resistivity, it’s a fantastic electrical conductor.
Copper is also an incredibly flexible material. Electrical connectors and wiring need to handle large loads of electricity at a time, but most metals that take on these loads don’t bend easily. Copper, on the other hand, has the ideal level of thickness to handle household levels of electricity, while still being manoeuvrable.
Lastly, copper is less oxidative than other metals. You’ve likely heard of oxidation when talking about rust. It happens when the oxygen and moisture in the air react with a metal’s surface. This reaction corrodes the metal which makes a film-like covering.