The galaxy has been, for billions of years and at all scales of power, perception, intelligence and activity, overrun with life. The geometry of reality gives spontaneous rise to minds and organisms, and they beget infinite variations of their kinds. Escaped experiments learn to breed, autonomous systems outgrow and abandon their creators, patterns self-select and iterate into extinction, ‘gods’ billions of years old delineate a living space in lesser minds, time and mutation turn every individual into an ecosystem, and always, new and ancient races build and fight and die. No matter how small. every niche is a fight to the death and nothing exists for long without gaining predators, prey, parasites, and infections. The cosmos is a rock, and when you overturn it, it writhes with life.
Whalefall is a sudden glut of resources stimulating an orgy of growth. Life operates as close to the edge of starvation as it can get away with, and when presented with surplus, gorges itself in a binge of eating and mating. It can only thrive, making the most of its find by packing itself with competition and variety, until you can't think beyond the smell of blood and rot and sex, until the glut is wrung dry and the ecosystem bursts, and the survivors return to a diet of starvation.
You said at first that things were better than ever, that grain quotas were being met faster than they could be set, that your fruits were larger and larger, and that everyone was having twins. Then you said it wouldn't stop, that crops were devoured by the soil, fruit rotted before they ripened, and that with every birth was discovered a new birth defect. Viruses, locusts, wolves, humans, everything thrives and swarms and mutates and speciates and you cannot survive with so much life.
You ask, why us? Why Earth? Why now?
There is nothing special about you, or this place. It is like this every time.
Humanity is a fruit, and it is almost ripe.
Notes: I have been vaguely dissatisfied with Strange Aeon for a while, and feel it needs to be refocused. I am making it less explicitly Lovecraft based, and intend to explore a sort of cosmic body horror.