Should Voyager I or II be found, the 3rd and 4th man-made objects to escape the solar system, these 115 images on the golden records will be all the visuals the discoverers have to go on about Earth and humanity. There is also audio including greetings, sounds and music (a few samples at NASA's website).
Assuming they'd be able to decode them, it's mind boggling to imagine what kind of conclusions they'd make from the photos. Would they think the string quartet, at the end, is operating weapons or building something? What would they guess as to our relations with the different animals? Would they figure out the plant-animal dynamic our planet has? What would they guess happens in the buildings so that we'd think it worthwhile to send images of them?
It's a lot of people, cultures, and animals in a well thought out progression. I hadn't seen any of the pictures until I came across the link. Initially I was surprised there aren't any shots of things like city skylines, landmarks, farms, more technology images, or even great works of art, not to mention writing and literature. I think the most useful image is probably the one of the woman with her hand next to an X-ray of a hand.
Then again, if you assume whoever would discover them will have at least as much knowledge and technology as we do, they'll have their own cities, civil works, and industries, too, which probably won't be all that different. Their stuff will be mass produced and made from the same elements*. The ideas of science, at least the physical sciences, will be the same for them. With that in mind, we probably did do a good job of selecting things unique to Earth.
* A very unlucky species would be one that arises on a metal-poor planet--I doubt they'd get to machines beyond windmills, waterwheels, and looms or even wide-spread electricity**. Maybe there's something that's common and useful elsewhere, but not on Earth.
** A friend and I, both engineers, one time had the idea that if electricity weren't practical, then we'd have to have shafts and belts or pressure tubes running everywhere to transmit power. There would be huge friction losses with any of those.