Radio is just a type of invisible light. We don’t have to “harness” a bunch of light waves floating around in the air to power our light bulbs - we make more light directly. Same thing for radio.

Think of it this way. If you want to talk to your friends with flashlights, you can turn them on and off in morse code. Likewise, a cell phone tower is sort of like a big “radio lightbulb” and it blinks really fast to communicate with your phone’s “radio camera”. Your phone translates that blinking it sees into information. (Oversimplified but vaguely how it works.)

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.

Man... Check this shit out...

So like everybody is saying, light and radio are just a tiny little segment of the EM spectrum... And yeah, there's stuff in the universe that emits all sorts of wavelengths, sure, but consider the visible portion. Gigantic stars, some that make our sun look tiny, are up there spewing out massive amounts of light, just like our sun does, yeah? And what we get here is just a little spot in the sky (don't get me wrong though, that's a long ass way for that light to project...). So the whole ass spectrum is gonna be that way, ya know? Like we get radio, x ray, microwave, uhf, VHF, and a bajillion other types of EM radiation from space, in little tiny points of a miniscule little signal...

Here on earth, we're generating massive amounts of this stuff. Cell phones, Bluetooth, the little electronic eye that opens the door at Walmart, we could sit here collective and toss out EM sources all day long and not cover everything we've built that's spitting out EM signals everywhere we go, right? It's mind boggling how much of it we transmit.

150 years ago, yes there were those little peeps in space we could have measured, but here on earth, it was pretty much dead fucking silent... The difference is absolutely fucking WILD if you think about it... A time lapse video of the past 100 years would look like an apocalyptical explosion :)

There were (and are) natural radio waves from things like stars and even something known as the Cosmic Microwave Background, the product of the Big Bang that created the universe.

However, they are not like rivers that we exploit for transportation, irrigation, and energy production. Instead, we have to generate our own radio waves to serve our specific needs.

In this sense, I find it useful to think of something like a lake. There are natural waves created by the wind, but I find it difficult how to imagine we would exploit those waves for communications because there is too much randomness built in and we have no control over the wind itself. On the other hand, it's relatively easy to imagine how we might create our own waves in patterns that can carry information.

An interesting thing about generating water waves to communicate is that it would be extremely difficult to make it work in practice. The waves degrade quite quickly over distance, so would need periodic repetition and amplification. Natural waves would mess up and possibly overwhelm our nice patterns. Other people trying to use the same body of water at the same time would be creating waves that would mess up and maybe even overwhelm our nice patterns. To get radio communications to work, people have to figure out how to deal with analogous problems with signal degradation and interference.

In short, yes. Consider that light is a form of electromagnetic radiation. So not only have radio waves been around for a long time, living creatures figured out how to use them for gathering data about their environment a long time ago!

Actually, yeah. But not in a way that we are harnessing or anything, more in that radio signals are also generated by stellar bodies and phenomena like stars, black holes, etc. The first time anyone ever turned a radio on, they got static which they didn't expect. That static is just cosmic radiation.

Light is an electromagnetic wave with our eyes being antennas tuned to the matching frequency.