Dream worlds - what are they?

So, I was describing my dream worlds to my guy today.

These are places where I go in my dreams that don't exist on waking reality, but I go to them over and over in dreams.

I started recognizing "Water World" - and calling it that, many years ago. Not only water world, but the road into Water World is kind of its own navigable place, too.

There was also the "Big Dream House".

More recently, there is a place I go that is a school/college ... we all live there in the dream like in a college dorm, but it has some halls with lockers that go on forever, like a high school.

There is also a mall world.

There is a subway world.

An "Alley World" with houses on both sides of the alley.

And my favorite is a vast indoor pool that's so big there's a whale and a beach ... but also like an observation deck and big ramps all around it.

Anyway, I searched GLP and found the mall world thread:

Thread: Anyone Frequent "Mall World" In Their Dreams

Not only was I blown away by the fact that this mall world sounds just like MY mall world ... I was more shocked to find that other people have been to the other worlds, too ... and their descriptions sound so much like mine, it's a little scary.

The big kicker was Bathroom World! I always go to Bathroom World - which is like a huge, nasty locker room ... on my way to the college.

Others in the mall world thread described the EXACT SAME THING.

What's going on with this? The skeptic in me says these are archetypes that are simply standard dream settings because we all have these shared experiences ...

but on the other hand ...

The bathroom world and college campus worlds described are EXACTLY LIKE MINE. And NOT really like real-life bathrooms or campuses ... meaning we wouldn't have experienced the weirdness that the worlds seem to share in real life.

What do you think is going on here?