How do plants that grow with artificial vegetative propagation grow in nature? Will they go extinct if humans stop intervening? e.g., Rose
Rose species reproduce perfectly well in nature, by the normal means of seeds and suckering. For instance, Rosa woodsii is found growing along streams throughout the western US: https://www.wildflower.org/plants/result.php?id_plant=rowo
The reason rose (and other plant) VARIETIES are propagated by various artificial means is primaily because they are selected for various factors, such as (in the case of roses) color, bloom size, number of petals, and (all too infrequently) scent. But those characteristics don't breed true: just as with humans, plants grown from seed will be different from their parents.
A second reason is that these plants are often hybrids of different species, and so may not produce fertile seed. Vegetative propagation - sometimes to the extent of using tissue culture - is the only way to get more plants of the same kind.
With roses (and numerous other plants) there's also a matter of economics. A rose hybridizer may grow hundreds or thousands of seedling roses to find one that might be a marketable new variety. When such a variety is found, the most economical way to produce many plants for sale is to graft the plant onto a common rootstock*.
*This is why many gardeners think their hybrid tea roses eventually "revert" to a boring red color. It's because they're grafted onto rootstock of the "Dr. Huey" variety, and the vigorous rootstock takes over if not properly pruned.