The Moon surface, on average, is about as dark as worn asphalt, with most of the rocks rather dark in colour. However, the sunlight there is very bright, not filtered out by the Earth’s atmosphere or clouds, and there is no dust to block it. The Moon has a very thin “exosphere” but it is so tenuous it doesn’t block out any noticeable levels of light. It’s so thin that atoms and molecules seldom hit each other traveling on long “ballistic” trajectories.

Asphalt can be quite bright on a sunny day. The photographs are white balanced to show the astronauts’ spacesuits as white, and they were indeed white, so I think it is reasonably fair to say that they give a pretty good idea of what it was like to human eyes - unlike Mars photos which are colour balanced to look more Earth like, to help geologists identify rocks there. Our eyes automatically adjust to see the brightest spots in the landscape as comfortable, not too bright, white, with our irises contracting to keep the light levels down if the landscape is very bright. And even when it’s cloudy, then we don’t see the landscape as dark, as our irises then open out to take in more light, so things then seem brighter to compensate.

They always landed in the early morning on the Moon, in the fourteen Earth days long lunar day. That’s because it was neither too hot nor too cold for human comfort, in their spacesuits, and the shadows were just the right angle to pick out the features clearly. Too early in the day, and the whole landscape would be covered in shadow, making it almost impossible to pick out features visually or to land by eye. Too late in the day and the sun is overhead, as they always landed quite close to the equator, which would mean hardly any shadows, so the landscape is hard to read again. They had a rather limited range of sun angles that were suitable for a manually piloted landing on the Moon.

I’ve experimented with adding blue skies to the Apollo photos, and it looks just like a landscape illuminated on a sunny day on Earth. So, I think the best idea of what it was like for them is to go to any rocky landscape, and imagine replacing the blue sky by a black sky, and that’s pretty much it - apart from the lower gravity levels of course, and lack of any atmosphere, and need to wear spacesuits.

See my What if the Moon had blue skies for more on this (section of my online and kindle book Why Humans on Mars Right Now are Bad for Science. Includes: Astronaut gardener on the Moon)