Lorule, Termina and the Twilight Realm are different dimensions/ universes. Koholint seems to be a interactive dream world unconsciously created by a fish god. The rest are either islands or lands within some travelling distance of Hyrule.
Hyrule itself appears to be apart of some greater land mass, although there are times it seems to be almost a peninsula. What is beyond it, really beyond it is unknown. What I notice though is that the further one gets from Hyrule the more round eared people show up, and the more advanced technology becomes (trains, pictograph boxes,etc.) The guy with the heavy winter coat in WW says he's a traveler from a distant land, and the camera he carries with him and the general vibe he gives off make me feel his technology is what you'd see in the 1920s.
There is New Hyrule, but that could be just an old continent that got renamed (since they seemed to forget a bunch other stuff) that used to be connected to Old Hyrule but get separated by the water.
What all of this is making me think, and this is going to sound like a maximum crazy theory to go with your question...
Hyrule and some of the places surrounding it is like Dinotopia. Dinotopia is a place that is seperated by isolation by being on an island and also by being partially in a different dimension. Dinotopia can only be reached on rare occasion, and thus because outsiders rarely reach it, technology is very limited, and it becomes almost quasi fantasy. They have very limited ideas of the outside world, and only by what other people tell them.
For Hyrule and some of these lands, it's the same way. They are of Earth (explaining the similar constellations) but are somewhat in an alternate dimension. They are quite isolated, with new technology coming almost incredibly rarely. Whatever ideas and technology they have of outsiders comes from the rare traveler that manages to breach this barrier, giving them pictograph boxes and and a few other things like trains. However, whatever technological advances people make within this place is often destroyed whenever Ganon(dorf) or anyone like him comes to town, tending to reset advancement back to medieval times.
The latest traveler to Hyrule in the Adult Timeline was the dude with the heavy fluffy jacket in WW. He brought the cameras. Someone earlier had introduced coffee beans. Although with the stuff in the Tower of the Gods, these eras could be waay past by now, and these people might have simply been 'caught in time' during their treck of where ever they were going (coffee guy probably shipping beans to the states during the mid1860s, and Eskimo coat guy was probably treking to the North Pole on an exploration grant during the 1920s and ended up 'caught.') And this next part sort of explains why.
For BOTW, this going to be far more advanced, with the outside world's currently at the year 3000 +. Sound crazy? It would explain the Shiekah disappearing, because they can travel back and forth through this breach. It explains the Slate and the ability to 'drip' data into it. It explain the ability to 'resurrect' a person, because the device would be able to reverse early decay (although the brain's memories being encoded by fragile neurons and chemicals, it was able to salvage most, but not all Link's memories) and the Shiekahs being able to utilize solid light and even mess with space/time. The time twaddling people have been doing might be bringing some folks inadvertently to this place, explaining the cameras and other odd 'old' technology in a place like Hyrule.
