I remember some book which devoted an entire chapter to Bio-Dome and its failure. The biggest problem, apparently, was that the designers “knew” more than the experts, so they screwed up in interesting ways. The excess CO2 for example, was because they thought if the calculated amount of compost topsoil was good, ten times as much would be better. This produced ten times as much CO2 as expected. Worse than the atmosphere imbalance, the high CO2 levels also caused deterioration of the concrete walls making it a risk the structure could fail.
They planted too many of the wrong kind of crops, causing an explosion in pest insects; the occupants then had to spend their waking hours removing insects from crops by hand, and still almost starved. Medical monitoring found dangerous levels of PCB’s in their blood - they starved so badly their accumulated fat was used up, releasing a lifetime of accumulated toxins that are typically stored in fat cells.
I also recall an article in Scientific American many moons ago, about the problem of dung beetles in Australia - or more specifically, the lack. Everywhere else, ruminants have beetles who “take care” of the cowpats they leave behind. Australia had no such insects, and instead huge tracts of grazing land were in danger of being paved over by accumulations of sun-dried rock-hard cow pats, aided by the excessively dry climate. There are plenty of other eco-imbalances to be found. Australia is famous for its rabbits. Cats and rats introduced by sailors have devastated a number of islands where the local animals have not evolved a defence. There’s one theory that says rats accompanying the Polynesian settlers, not competition for log rollers for statues, destroyed the forests of Easter Island; the rats ate most of the nuts that fell, removing the forest’s ability to regenerate.
So no rats…
However, I would suggest the Darwin’s Finch approach. Horses don’t morph into tigers. To have an ecosystem self-adapt, it needs “starter kits”. Give it some small, simple, basic, do-all animals like plain sparrows and field mice and let them over time evolve to fill any missing niches. …Which is a great concept, until you have to fight the mice devastating your crops. But then, that applies to any smaller herbivore. They’re going to eat where the herbi- stuff is.
For food animals, perhaps the goat is a good choice. Feral pigs can grow to be dangerous. Cows are too big and take up too much resources. Sheep cannot survive easily without humans shearing them, Chickens might be OK, but then they’re likely toast as soon as you release a predator.
Also, if you’ve created an entire world, you mostly want to seed a non-domesticated animals to create an ecosystem. That means a wide variety of “starter” animals. They have to be introduced in stages. The forest needs to be there before the birds, the grass before the deer or goats. Fruit trees would be nice, but they tend to flower and need insect pollination. (You cannot pollinate an entire world by hand). The trees you pick have to be able to spread their seeds; so does the grass, otherwise all you get is wall-to-wall dandelions. Maple trees have those winged seeds. Oaks rely on squirrels to grab their nuts. Blackberries are spread mainly by birds and small animals, IIRC - but enough fall nearby that untamed blackberries can generate incredibly spread-out thick bushes.
For fast, practical wood - I would suggest bamboo, the stable framing material for huts across the far east tropics.
But then, we haven’t talked about soil. There are marginal plants, lichens, and similar organisms that will grow with a minimal amount of real soil, then eventually build up to decay and produce real soil for the next generation. From what I understand, the fossil fuel of this generation is the result of buried detritus of past eons. Much of that burial happened before the evolution of grasses, when widespread mudslides and heavy silt deposits were much more common. A lot of rich eco-action happens in tidal pools and especially deltas, where the washed-down organic matter from an entire river basin concentrates in a delta, with plenty of water to sustain life too.
We also haven’t discussed the ocean ecology. There’s plankton and algae, which get their nutrients from the ocean and become a food source for higher animals. I would suggest starter animals again, some smaller fast-reproducing fish that can eat the plankton, and something like minnows for fresh water. Given abundant food sources and fast reproduction cycles, expect them to diverge into species that can accommodate every niche.
Again, there’s the question of whether and how to introduce a predator species. Without one, you risk a boom and crash of the prey species. With it, you risk the same thing happening to the predator species. My understanding is that the most important thing is that the prey recognize the predator and be evolved against them. Many of the ecological crashes were for lack of defence. Moas and dodos were not designed to escape humans, even if they had recognized them as dangerous. Seabirds nesting on small rocky islands had no time to learn or opportunity to hide their nests and chicks from introduced rats. Small fish can hide from larger ones in reeds and seaweed. Rabbits outrun wolves, burrow to escape owls etc. (There’s another problem - burrowing animals need soil that can be burrowed)
Fortunately, with a huge world, you can experiment on various islands to see what works or not, before turning that animal loose on the mainland. But never forget, too, how many thousands of different ecosystems there are in one world. An animal adapted for one climate or landscape will not necessarily do well in another.