Electrical – Why does a single switch on the wall control only the fan on the ceiling fan

Absolutely do not leave the wires alone wrapped in electrical tape. Electrical tape does not have enough longevity to safely protect the exposed leads and can create a hazard in the future.

The blue wire exists to support the future addition of a light. The polite thing to do for your future self or future owner of your home would be to connect the blue and red wires. However, it is not necessary; if you do not want to, you can cap both leads with wire nuts.

Note that it is also legitimate to connect the black on the fan to the red from the ceiling, and the blue on the fan to the black from the ceiling. Assuming you have two switches, that will swap which switch controls the fan and which switch controls the light.

If the existing black-black connection doesn't work, you can try the black-red. If that does work, it would suggest that the switch for the fan has failed, although it could also indicate other wiring problems.

The only product that I know of that will do what you want is the Lutron Maestro Light/Fan control. This product consists of a switch and canopy module. The switch will digitally talk to the canopy module over the single ungrounded wire and control lights/fan separately. The kits are one switch and one module but the switch can talk to 4 modules at once.