I really wanted to give this 5 stars just for the sheer novelty of the work (and the fact I binge read it in one day, so you know it's decent) but couldn't quite because I think there were a few flaws in the handling of the human and aliens. There was not enough variety in personality: it just did not make sense to me, in this world where you can find tentacle porn fetish folk (in fairness maybe the author didn't know those people existed?), that every single human would flinch from the aliens on sight, or that they would have to be so damn coercive and have to force /all/ the humans to have no options but to breed with them in order to crossbreed! Similarly, you'd think a sapient species would have at least one or two conscientious objectors or weirdos instead of all of them universally agreeing with each other in a species that is /supposed/ to be anti-hierarchy. I get it, they're mucho into democracy, but democracy doesn't mean no disagreements. Or perhaps the one alien dude who volunteered to let Lilith kill herself was that one mutant, whatever.
If 'bang every human you can' is really a universal drive in them as much as wanting to bang in general is in humans (although the actual metaphor is 'can you hold your breath forever?') it would have made sense to have a mutant, since ace people exist and the aliens explicitly said they saw value in genetic diversity so sometimes weird combos of genes could act unexpectedly (if cancer was so novel to them, they clearly didn't know everything there is to know about genes already too). Not all mammals have involuntary breathing and these guys go out of their way to mix with different species from different planets, I just don't buy not a single one of them would be a mutant who is hiding the fact they don't like what is effectively raping people and would want to work to free humans. If this is a colonialism metaphor, then it's one where for some reason there are zero abolitionists.
The other thing I don't like is the total lack of any queerness in a work that has three genders, and all the men having a homophobic reaction to the third gender aliens. What the heck is up with that? Was she worried that homosexuality would somehow be less acceptable to an audience than tentacle p0rn threesomes?
Well, maybe it would be, I don't speak bigot.
I also felt frustrated there weren't any human genetic engineers, but some of this might be because I read humans as being closer to our current level of gene editing where a sufficiently determined knowledgeable person probably /could/ CRISPR a baby to remove foreign genes, whereas even a decade ago that wouldn't have been very plausible, so I may have simply misread the tech level of the people. The aliens said they removed human ruins but not all of them, so you'd just need one paranoid person who had a hidden stash of goodies somewhere the aliens didn't manage to find that included some CRISPR tech. If I were the aliens I'd probably be careful not to choose any humans with genetic engineering knowledge, or if I did, to make sure that human didn't end up in a group with one of those machine engineering fanatics, minerologists + doom prepper and SCA/historical-re-enactment type fans who might actually be able to re-build shit like very basic computers and metallurgy from scratch if they had to rebuild civilization.
...That would have made it a very different novel admittedly, and now I have an itch to maybe make a fanfic or something at some point, or expy of the aliens novel that just takes the premise and runs with it differently.
I guess I just never take it very well when aliens or anyone else tells humans they are too stupid to comprehend or do something. You only need one genius to fuck that story up.