But wouldn’t it be great if we could view the Earth as it was in the distant past and actually see how these and other creatures looked? Say there are aliens on some other world millions of light years away peering at the Earth from ultra powerful telescopes. Scopes so powerful they can make out clear images of the Earth’s surface and inhabitants from such distances (likely impossible, but who knows). They would actually be able to see these things going on before their eyes, or whatever means they had for perceiving optical light waves. One at a distance of, say, 100 million light years would see live dinosaurs roaming around. 4.6 or so billion LYs, the Earth in the earliest stages of formation.
...they(the aliens) would in theory be seeing Earth’s past at this very moment in time(now). Because it would have taken that long for the light from the ancient events to have reached them. This sort of thing happens all the time when astronomers look out into the universe. They see stars and other galaxies as they were in the distant past, in some cases from billions of years ago.