You're saying it took a thousand years to create humans,
Try 500 million years.
One of the animals that is shown fairly consistently in the flashbacks is Anomalocaris. A good choice, since it is the oldest top predator known, and is even pretty scary by our standards: a proto-arthropod (?), between two and seven feet long, with curved, segmented and barbed jaws, the size of human hands.
However, Anomalocaris is known only from the Burgess Shell fossil batch and that is over 500 million years old. In other words, it took the Uranus at least half a billion years to develop humanity.
Personally, I believe they did it in several main phases, each one ending in a mass extinction...
1 - (end of the Cambrian) After the trilobites, protoarthropods and early chordates proved a disappointment, most of them were destroyed so the strongest could develop in the open spaces.
2 - (end of the Ordovician) The former was deemed a failure, and the remnants were purged again. Interest shifted towards vertebrates.
3 - (end of the Devonian) Fish were deemed to develop too slowly. Most of them were made extinct to give the bony fish more space.
4 - (End of Permian) In order to favor a specific group of reptiles, considered to be extremely promising, nine tenths of all species of animal were purged.
5 - (End of Cretaceous) The dinosaurs, once the crown jewels of the project, were finally rejected for being too large and genetically stable. Final stage of project starts with their extinction.
Also... 20 million years ago the Uranus left? Um, no, that is impossible.
When they left, what they left behind were either modern-day humans, Homo Sapiens, or our immediate ancestors, Homo Erectus. In any case, this cannot have been more than one million years ago.
Twenty million years ago, there weren't even hominids yet. Also, twenty million years ago the modern series of ice ages had not yet started - that began about 2 million years ago.
200,000 years would be infinitely more probable. That is around the time the first modern humans appeared.
In any case... I don't think the Uranus would have very much more advanced technology. It is clear from their incredibly slow advancement in the development of humanity that they think very slowly, compared to us. They probably live very, very long lives.
By comparison, we may very well be like bacteria. We live very brief lives, but we breed insanely fast and we think very fast as well. Hello: from heavier-than-air flight to space travel in fifty years! Also, we are barely sentient by their standards, but we are still incredibly dangerous! Just like a strain of bacteria. We are bio-weapons, after all. We are the cosmic equivalent of anthrax!
All this makes the existence of the Guyver very puzzling. How could they make such an incredibly stupid mistake after all that work??? 500,000,000 years in the making and they all screw it up in a single hour. What a bunch of cosmic idiots.
Maybe, if Archanfel ever manages to build his fleet and find his masters, he might find that they were destroyed by their enemies... or that we are superior to them by now. Heck, if you have a 30-mile ship full of battle-ready super-humans (which is what Zoanoids are, after all) who have nothing to do for the years it takes to travel through space, they might well come up with some surprising new technologies.
Why not create Zoanoids that are physically feeble, but incredibly intelligent and inventive, while still being subservient to Zoalords?
Has anyone ever read Larry Niven's "Protector"? That's sort of what I am talking about. (Well, a protector is not physically feeble...)
One more thing.... People keep calling the planet the Uranus tossed at Earth a "meteor". Maybe it was a meteor in the strict sense, but I must reiterate that it was the size of a planet. I also read "Moon-sized" over and over again, but it is clearly half the diameter of Earth itself... the size of Mars, and significantly larger than even Ganymede, the largest moon of the solar system. They really wanted to be sure we would be dead.