yes, they have been there but the question:

Just waiting to be harnessed and used for a purpose?

Is a bit problematic as what humans use radio waves for is to encode information while natural radio sources are noise (random fluctuations without encoded information.)

From Wikkipedia:

Cosmic noise

Cosmic noise, also known as galactic radio noise, is not actually sound, but a physical phenomenon derived from outside of the Earth's atmosphere. It can be detected through a radio receiver, which is an electronic device that receives radio waves and converts the information given by them to an audible form. Its characteristics are comparable to those of thermal noise. Cosmic noise occurs at frequencies above about 15 MHz when highly directional antennas are pointed toward the Sun or other regions of the sky, such as the center of the Milky Way Galaxy.

Celestial objects like quasars, which are super dense objects far from Earth, emit electromagnetic waves in their full spectrum, including radio waves.

The fall of a meteorite can also be heard through a radio receiver; the falling object burns from friction with the Earth's atmosphere, ionizing surrounding gases and producing radio waves.