It wasn’t infinity in fact. Infinity itself looks flat and uninteresting. Looking up into the night sky is looking into infinity—distance is incomprehensible and therefore meaningless. The chamber into which the aircar emerged was anything but infinite, it was just very very very big, so big that it gave the impression of infinity far better than infinity itself.
The forest is immensely vast in its scale. Billions of trees spread across its acreage; billions of plants line its floor; billions of people walk its paths. But homogenous it is not; to catalogue the variety of all of its fractal of objects in every one of its crevices would require a library as enormous as the forest itself.
The forest is shaped by its inhabitants; wherever one walks one can find communities gathered, doing any of a vast array of activities in whichever space they have carved out for themselves. When people cannot find a free place in the forest, they will take the seeds the forest grants its inhabitants far away, planting them elsewhere to grow a place for themselves, expanding the borders of the forest evermore.
These communites that shape the forest so are not isolated. Indeed, interconnection between these communities is plentiful—some even say that it's the only thing that gives the forest its life. Sure, one may sometimes find a run-down path or a path to nowhere, and sometimes the signs which point the paths say falsehoods, but if one stays in the places of repute they shan't find themself lost easily.
The people aren't the only thing in the forest, of course; throughout the forest one can find a menagerie of flora of many colors, many shapes, many sizes, all put together in many, many, many combinations. One could easily find themself spending hours in even just a small patch of the forest, smelling all of the flowers and tasting all of the fruits that the forest gives.
Many people will often find themselves interacting with the plants in other ways, too, rearranging, planting, and picking the plants, shaping little corners of the forest for their own leisure. Sometimes, people will go so far as change the plants, either turning them into strange new objects or creating wholly new plants to decorate the forest.
Of course, as there is flora, such is there fauna in the forest. Many a community have strict rules in place to keep the beasts of the forest out of their borders. But some have managed to tame the creatures, and when trained people will often be granted special permits to allow these creatures inside. Particularly well-trained animals are often just as well-respected by the communities they inhabit.
That in mind, not every creature is trained in such a manner. Some creatures are trained instead to follow the trails of the forest and seek out information about what they find, bringing it back to a central base of operations for cataloging. While initially such training was something of a gray area in the laws of the lands, today such creatures are generally tolerated, and most communities are prepared for them—in fact, tapping into the catalogs brought about by the efforts of the creatures for information is nowadays considered an expected part of existence in the forest.
There are many communities in the forest, but most of them are small things without many people active in them at all, and most people find themselves in only a minuscule fraction of the communities in the forest. But not every community is so; some have grown to truly enormous sizes, to the point that it can feel like almost everyone in the forest is in at least one of these monsterous collectives. These communities have immense influence over the entire rest of the forest, and are of such an immense size that they've found themselves subdividing into subcommunities, as if creating their own forest within the larger one. With such size comes organization; some say these communities feel more like cities than a part of the forest.
It wasn't always this way. There were always some communities that were bigger than others, of course, but the size differences used to be much less intense. Never would people have thought that any sizeable chunk of it would be controlled by a single entity. People who still remember that time can still be found in the forest today, sometimes having acquiesed to the large communites, but sometimes still remaining in the more wild parts of the forest; their fond remembrances of long-ago times are seen by many as naïve at best and regressive at worst.
The wilds of the forest still exist, of course, but they're not as prevalent as they used to be. Many of the little things built in the forest when it was younger are nowadays being consumed, rotting away into the wilderness from which they were built. Some people still try to make things with the techniques used long ago, but most of the time people don't; they quite like to do things the same way as everyone else does nowadays, even if it's less flexible and produces more crap, because it's more convenient—or, more cynically, because everyone else is doing it, so they implicitly assume it's good.
Some people have tossed about the idea of burning the entire forest down and letting it grow back to restore it to what it once was. This would be difficult; subsets of the forest have been set ablaze before, but they've always ran themselves out naturally before they could get very far. Moreover, the biggest communities nowadays have teams in place to combat fires like that; turning them to ash would almost certainly require extraordinary luck to time the burn with a catastrophic mismanagement decision. Setting the whole forest on fire wouldn't be a matter of dropping a match and letting it spread; it would require agreement from every community to abandon their works in the forest to ruin.
Of course, the forest itself wouldn't care. The forest has tendencies, and when the people of the forest have noticed them, they've often framed and promulgated them as laws—but they're not. The forest has no laws of its own. Communities have made their own laws, but they only reach as far as the voices that speak them and are only as strong as the arms that enforce them. Many a time has a dispute of the laws in a community been resolved by the people abandoning that community for another, walking away from even the jurisdiction of what seemed like the strongest of dictators.
The future of the forest isn't certain. Perhaps the biggest communites will fracture into a million pieces, sending the forest into a new wild era not unlike what it had been like in its younger years. Perhaps all the communities will fuse into one, staying that way until a madman takes power and throws everything into catastrophe. Perhaps the forest will continue in it's current state of general mediocrity for a good while longer. But the forest itself isn't going anywhere; billions of sets of feet will surely tread its paths for a very long time to come.