Planet fill up with prehistoric ET aliens' descendants

Scenario: Once upon a time, almost 100 million years ago, a distant planet in the Rigel star system underwent an extraordinary transformation. A group of advanced, prehistoric time-traveling aliens known as the 'Terraformers' chose this lifeless, barren planet as the canvas for their ambitious project. The Terraformers were a benevolent species with a deep connection to nature, with knowledge way above human comprehension. They could manipulate DNA, control biological life cycles and were experts at temporal displacement. Their mission was to spread life to different parts of the universe. On reaching the Rigel planet, they began by engineering an earthly-like atmosphere and replicating the water cycle. Once conditions were just right, they started on the more substantial task, the introduction and propagation of life. Using their time-traveling capabilities, they harvested genetic material and specimens from numerous species on Earth. First, they brought types of fungi and plants, utilizing their symbiotic relationship to develop the planet's soil composition and creating a balance of gases. As the flora thrive, they introduced invertebrates alongside fishes in the vast oceans they had created. As the ecosystem was gaining stability, they introduced amphibians and smaller reptile species. The Terraformers' advanced planning came into play here. They introduced the dwarf caimans, a species that could survive in both terrestrial and aquatic environments to control the amphibian population, balance the ecosystem and keep the food chain in check. As the fauna started evolving naturally, they brought the larger herbivores. They introduced elephants, hyraxes, manatees, dugongs, rhinos, and tapirs, alongside a myriad of grassland and forest flora. These mammals served both as seed dispersers for the plants and the larger prey for forthcoming predators. The Terraformers then introduced carnivores like wolves and mongooses, and omnivores like lemurs, bushbabies, lorises, and apes. Each addition was carefully timed, allowing the newly introduced species to adjust and thrive. The introduction of armadillos, sloths, opossums, possums, quolls, bandicoots, bilbies, numbats, the Tasmanian devil, koalas, wombats, wallabies, kangaroos, platypuses, and echidnas, helped in further diversification of the environment, enriching it. Over the span of several million years, the planet's ecosystem diversified naturally with the descendants of these initial species, with the Terraformers overseeing and nurturing the constant evolution. Today, the once barren planet in the Rigel star system thrives with a rich biodiversity, parallel to Earth's own, thanks to the intervention of these ancient, time-traveling Terraformers. Each species that inhabit the planet now trace their lineage back to those first terrestrial voyagers, a testament to the ingenious project of these alien caretakers.