There is no "in real life." The size, sensitivity, and spectral response of human eyes is a response to the radiation conditions on Earth, as enhanced by evolution.
If the Sun had been redder or bluer and your eyes were the size of your head or much smaller, everything would look very different.
The Webb images are infrared so "in real life" you'd never see them as shown here. You'd see whatever was visible in optical wavelengths.
This isn't just a quantitative difference. Those science fiction imagined alien worlds covered in little tiny technological lights - just like Earth - are a fantasy. Aliens might see UV instead of optical frequencies, and Earth would look like Venus to them - an opaque planet covered by a thick haze. They might light their spaces with UV, which we wouldn't be able to see so their planet would look dark to us.
It's the wrong question to ask because a 'human observer' would see absolutely nothing. The age of the objects you are looking at is such that you are looking into the past not at something the is still there in the present, so if we were to transport you there you would not recognize the various objects in visible light at all, too much time has passed.
This isn't true at all, many of the objects are not far away.
The Carina Nebula (imaged) is 7,500 light years away. It is still there.
It seems like people are going through mental gymnastics to avoid answering the question. If someone asked what a famous black and white photo like raising the flag would look like in person, would people give the same nonsense answers? e.g. "There is no "in real life", "the past cant be seen"
For the Carina Nebula[2] :
"Several filters were used to sample narrow and broad wavelength ranges. The color results from assigning different hues (colors) to each monochromatic (grayscale) image associated with an individual filter. In this case, the assigned colors are: Red: F444W, Orange: F335M, Yellow: F470N, Green: F200W, Cyan: F187N, Blue: F090W"
This is in comparison to the human eye, which sees 630 nm for red, 532 nm for green, and 465 nm for blue light.
That is not to say the Nebula isn't also observable in visible light, you would just be seeing different colors and perhaps features. probably something like this visible spectrum imagine of a different part of the nebula
For the other images, what you would see in person ranges from very similar to nothing depending on the image, and pixel in the image.
Yes, you're right, for that particular nebula. Of course there are other nearby objects that are interesting in that spectral range. But MIRI really shines when it comes to distant galaxies whose light is so far redshifted that it shows up as deep infrared.
Although the accuracy of infrared, or other non-visible spectrum digital representations, could be disputed you would definitely see something similar in visible spectrum as compared to infrared, but with much more dust. Most objects that are emitting energy are doing so in many portions of the spectrum.
> if we were to transport you there you would not recognize the various objects in visible light at all, too much time has passed.
I think this is an old interpretation of the speed of light and spacetime, since it describes travelling very far through space and also time. So it's more of a statement about the realities of space travel than what it would be like to be there now.
As you said, distance = time, so saying that too much time has passed is the same as saying that it's too distant to see, which is kind of beside the point.
I would say that what we see in the pictures really is the nebula as it exists now, but if you tried to travel there at near the speed of light, your speed through time would increase so much that you would see it rapidly change.
The real question is, what would you see if you were there now (at the time during which the shape of the nebula matches the photo).
If the Sun had been redder or bluer and your eyes were the size of your head or much smaller, everything would look very different.
The Webb images are infrared so "in real life" you'd never see them as shown here. You'd see whatever was visible in optical wavelengths.
This isn't just a quantitative difference. Those science fiction imagined alien worlds covered in little tiny technological lights - just like Earth - are a fantasy. Aliens might see UV instead of optical frequencies, and Earth would look like Venus to them - an opaque planet covered by a thick haze. They might light their spaces with UV, which we wouldn't be able to see so their planet would look dark to us.
And so on.