Unless we are mistaken regarding the laws of physics, they are going to be using a communication system that takes years to travel. Light speed is a hard limit, and outside of fiction,even the most technologically advanced civilization isn’t going to be able to break it any more than the most advanced mathematician could find the last digit of pi.
Haven’t they suffered enough? Ignorance is bliss.
As I recall it, it wasn’t “slavery” in the sense of the chattel slavery of the 19th century, but rather more like a species-level indenture. So it’s not like individual members of a patron species would have individual slaves of the client species or anything like that. I viewed it as being more along the lines of owing feudal-style obligations- to go to war at the behest of your patron species, provide a certain number of your people to do certain tasks you’re skilled at, etc… And your species doesn’t sit at the grownup table in galactic society. That’s probably the biggest one- your species is basically spoken for by your patron race.
Earth’s status in the books was that we were a “wolfling” race, meaning that we had self-uplifted (which was all but unheard of), and had uplifted chimps and dolphins on our own, which gave us a place at the grownup table without a patron race of our own.
The biggest one is that the patron race can continue to keep modding the client race in any way they’d like to, until the period of indenture is over. The books have multiple examples of extremely cruel changes to client species. Startide Rising itself had an example of a species that was so grossly changed that every moment of their existence was agony. It’s given as an example where other races actually forced the indenture to be ended early, but there are many examples of purpose-modded client species in later books that don’t get any reprieve.
So, it’s 100,000 years of someone else forcing your children and all their descendants into neverending body horror.
As I recall it, it wasn’t “slavery” in the sense of the chattel slavery of the 19th century, but rather more like a species-level indenture. So it’s not like individual members of a patron species would have individual slaves of the client species or anything like that. I viewed it as being more along the lines of owing feudal-style obligations- to go to war at the behest of your patron species, provide a certain number of your people to do certain tasks you’re skilled at, etc… And your species doesn’t sit at the grownup table in galactic society. That’s probably the biggest one- your species is basically spoken for by your patron race.
Earth’s status in the books was that we were a “wolfling” race, meaning that we had self-uplifted (which was all but unheard of), and had uplifted chimps and dolphins on our own, which gave us a place at the grownup table without a patron race of our own.
Why would you assume that we actually understand them completely in the first place? Well over half of all the matter in universe is believed to be “Dark Matter”, and we have absolutely no idea what it is or how it works or how it affects our visible universe. We also do not have a Quantum theory of gravity that connects to Einstein’s theory, so that also is a big gap.
Also, the “nothing moves faster than light” statement is not true. If you warp space, the end result is that you are traversing a given distance faster than light.
I’m going to leave the rest of the “technology-optimism of the gaps” alone, but “how it affects our visible universe” is how we know Dark Matter exists, so saying we have absolutely no idea is very wrong.
Why on earth are horses at the top of your list? They seem dumber than rocks.
Substitute octopus for horse, and that’s a pretty good list. I think the octopus and the birds would be the most interesting, because they are the most different from us.
Cats are definite no. That’s just too frightening. There no chance whatsoever that they would use their new-found powers for good.
Horses are smarter than you think, but I didn’t order my list. Just wrote them out. In fact it looks like I started with less intelligent candidates.
I would no sooner uplift Octopuses than Cuttlefish. Both are too alien and probably even more dangerous than uplifting cats.
There are also two excellent sci-fi books about uplift by Adrian Tchaikovsky - Children of Time, and Children of Ruin. I won’t give away the species involved in each book, but they are unusual. The scientific mechanism is hand-wavy (nanovirus mumble mumble), but what’s superb - especially in the first book - is how imaginatively the story is told from the perspective of the society of animals that are uplifted. It happens accidentally subsequent to a human plan to uplift monkeys as part of a terraforming project, and the process occurs over many generations in the absence of humans.
Huntsman spiders. Hilarity ensues.
There were better and worse patrons for sure; the Tymbrimi and the Thennanin were pretty good, as was EarthClan, but the Tandu were horrific.
You’ve seen THEM.
I read “Children of Time” recently, one of the best books I’ve read in a long time.
If our purpose is to get somebody interesting to talk to, I think more alien is an advantage.
We’d need to be prepared to give up dominance of the oceans, though. Which, considering what we’ve been doing to them, would probably be a good idea.
Strictly ethically; wouldn’t the OP:s proposal be the exact equivalent of implanting the brain of a human fetus or newborn child into the body of a non-human animal?
I don’t endorse it.
Seems to me that chances are the discussion won’t be all that interesting. Yeah, yeah, we all agree that 1+1=2. So what about shape-shifting and color change – how do you octopus do it? Pretty much the same way you humans sneeze!
I’m not sure an intelligent species would necessarily need the same resources we do; and since I don’t see anything restricting which “species” can be uplifted, I’m going to pick Ficus elastica. There are already living bridges; I imagine humans in a symbiotic relationship with living, sentient homes.
Eh, I don’t give a fig about them.
Time to step up and be contrarian 
Is this just the premise of this OP, or something that you’re asserting? Because if it’s the latter you’re asserting something we cannot know at this time.
IMO, no, I don’t see much to gain by making another species humanlike.
A different kind of intelligence / superior intelligence? That would be more appealing and is the more likely situation in reality (it’s implausible to think of scenarios where we can engineer exactly human level intelligence, no more no less, and no amount of investigation or research ever changes this).
The issue is a bit bigger than that though. Because humans, probably within a millenia or so, will possess the technology required to litter the galaxy with bric-a-brac, even assuming a light speed barrier.
If there are lots of technological species out there, it’s strange that the galaxy still looks like a blank slate.
We can speculate reasons why that is the case, but we don’t know, and that’s fundamentally the fermi paradox.