Oooooh, the whole concept of divinity being "pollution" is super fascinating. Is it like, actively harmful or is it just causing weirdness that then becomes harmful? (For example, does it kill people/animals that drink the water, or does it just make everything that drinks the water glow and turn in potatoes.)
How does it make the Earth unstable? What's the "last straw" that forces humanity to leave the planet? And since you said this all happened in the 1860's (or 1640's?), does space travel get invented earlier than in our universe (since technically we haven't perfected long-term space travel yet), or do things just not get Really Super Bad until ~200 years after that?
Also, is the Earth completely uninhabitable? Or are there still people and/or animals left down there? How far in the future does Starcrumbs take place? Is there a good record of how all of this happened, or is it mostly legends and guesswork?
Sorry for the massive question spam. I'm just absolutely fascinated by this WIP now!! Consider this a mega WBW ask, I guess!
~Morri🗡 (@memento-morri-writes)
HELLO Sorry it took a while to answer, I love long questions btw - you absolutely made my day!
1 - is divinity poisonous or does it just do weird stuff?
Yes and yes! To answer more coherently, it does weird stuff, but, above a certain concentration, the weird stuff becomes quite certainly deadly.
Divinity conducts 'miracles', or changes the properties of things in ways that should not be possible. Uncontrolled divinity usually tries to make all things equal, turning unusual instances, like living creatures, into the more 'natural' state of things, like mud or water. Fun fact - this is also how space is created! Ancient giant gods that look a lot like whales travel through space, and through their large concentration of divinity naturally create more of similar space around them.
Back to out question, if a human plummets into a liquid that's 30 or more percent divinity, they'll probably turn liquid. Is it's 10%, they might turn into a fish or another aquatic lifeform, and 1% would mean drastic changes to their physiology. 0.1% and under, however, would mean that the human would gain some water-related properties, from transparency to being able to breathe underwater, without changing their shape - pretty neat and kinda cool! A lot of research went into making those changes more controllable. The smaller the concentration, the more tame and favourable the results. Trace concentrations would still have noticeable effects.
2 - How do humans fuck up the earth? When do they abandon ship?
Earth gets seriously messed up during the 1860s-1870s because of
1) a select few countries trying to conduct experiments with divinity, which resulted in divinity contamination (areas where the local water and soil gained too high a level of divinity for it to not warp humans/animals/plants) and
2) divinity wars, which were caused by the other countries trying to get access to said divinity-containing material, aka a part of the angel's corpse (yes, they all fought over the corpse of one (1) angel.)
This resulted in most of North America and Europe being kind-of-not-habitable, and the rest of the world slowly experiencing the changes as small concentrations of divinity spread through the oceans, plus divinity powered weapons being... quite destructive.
The final drop that made people start leaving, however, was not necessarily a bad thing, and here we get to question no.3
3 - divinity, science and space travel
Having a gimmick that lets you bypass the laws of physics but comes with its own set of eldritch rules makes technology develop in bizarre patterns. For example, flight, including space flight, was exceedingly easy to master, seeing how the divinity stored in angel's wings already provides with flight capabilities, and things like pressure, heat, and atmosphere can be hand waved by infusing humans with tiny amounts of divinity until they adjust to their surroundings.
Telescopes, microscopes and all thing sight were also easy to make with angel's eyes, and the great migration began when someone spotted an angel in space - something of a second gold fever, the idea of space travel and angel poaching as the new course for humanity's development became the frenzy for the 1870s and early 1880s. There are, in fact, still humans on earth, some parts of it are in fact habitable, but the previous socio-economical and geopolitical environments are more or less nonexistent.
4 - how does the history look in-universe in Starcrumbs, and when does it take place?
Starcrumbs is technically set in the near past, the 2010s, although the alternative history splits quite far from the modern world for a number of obvious reasons.
There is no set history all people agree on - those that stay on earth mostly consider the angel's appearance a sort of test most of humanity failed but their ancestors didn't, a near-apocalyptic event to weed out the wrongs - the less religious ones consider it a sign of underlying tendencies of human nature. Still, the general earth-dweller consensus is "earth folk good, space folk not as good".
The beliefs of those that migrated to space and quite different, seeing for the solar system in an agglomeration of Holy Roman Empire-esque tiny state-settlements, but the general gist of it can be summed up to "earth-dwellers backwards and counter-progressive, space-dwelling and divinity gathering (not known as angel poaching because that sounds unseemly) good and progressive".
Sorry if I missed any points! This was super fun to think about, I have a better feel for the world now and would be glad to clarify on any points :-]