Now hold on, a second. Looking back to the brief intro scene, Ralph and Van willingly enter, knowing that it’s a game. Van uses a Beta Key to get in, so we know and they knew that it was unfinished. I don’t have any theories, but here’s a few tidbits of what I could put together.
DISCLAIMER: I’m on S19, so there may be lore details in newer chapters I don’t have access to that invalidate all of this.
Since she has no memories of anything in the city, that means she couldn’t have gone in to get the key. Either the Inventor has associates outside the game (or at least, can leave it), or the in-universe dev team left it out there. Remembering back to what I can recall from the older campaign levels, I think the other heroes (all of whom were in the game from Beta) didn’t remember how they got to the city, while Van remembered the key. Just a thought, but: maybe the inventor/devs started testing the game by manually bringing in the beta heroes, before Van got the beta key from wherever. After that, new heroes started wandering in through the open gate, from the internet (in the WIR universe). This would closely mirror the game’s history: there was beta, then global release, and now new heroes join every so often.
Remember back in the tutorial, when Van’s turned into a creep immediately? And there’s a point in the story where she starts to turn again when the Inventor touches her. Something about that raises an eyebrow. You could chalk this up to losing to creeps immediately and the inventor’s oddball powers, but in the friendship campaigns there’s constant creep-genocide*. Since collecting chips to unlock heroes is canonical within the story (as we know from the tutorial), and that’s how they un-creepified Van, it can be assumed that every new hero is immediately turned into a creep. So what’s the deal? It can’t be a coincidence.
*Unrelated, but I get why they cut friendship content back to just dialog. 90% of it was just fighting the creeps as overused filler content. Disney’s ever-watchful eye having to approve everything probably didn’t help much either.
Another thing, isn’t it kind of weird how distant the main campaign and friendships are? The heroes truck through what’s made out to be a brutal wasteland where the full roster of heroes can’t hold them off forever. Then cut to friendships, where we learn that WALL-E and EVE have a community garden, there’s a library and functioning government system with public services like a police station, most people (at least the Incredibles and Felix/Calhoun) own homes, and two heroes can go through a swarm of creeps like a can of Raid through an anthill. I get that the later levels move on to secret levels in the city, but it’s very weird.
Then on top of that, creepified heroes literally never appear in friendships. I’d have thought that fake copies of heroes would have been a philosopher’s stone for creating campaigns, or that there’d be at least a few that bring it up. What if the friendships take place, chronologically, after the heroes have defeated the Inventor and stopped whatever was turning heroes to creeps?
Since Disney is a canon company in WIR2, it can be presumed that their movies are as well. I’d say it’s not out of the question for them to be dragged out of them and put into the city. And if they figure that out, there’d be some existential questioning being tossed around, probably deciding to stay in the city. And, well, we all know that they can’t just go home, then the game wouldn’t make any sense.
Again, disclaimer, I’m not fully up-to-date with the campaign, and there’s always the possibility that one of the hundreds of friendship campaigns has something I missed. These may be off.
But it isn’t just pulling people from the real world. The toys are pulled, emotions are pulled, characters are pulled from multiple places in their timelines, whole places are pulled into the city, or programmed into the city. Islands do appear in the campaign map at later times.