First contact could have gone better.
The beings visiting Earth had learned how to leave behind their physical bodies so long ago that the idea of an awakened mind being tethered to meat was at best quaint, and frankly, a little disgusting to them. How could one explore infinite space, or spend the required centuries on the really worthwhile philosophical questions, when still stuck in all that biomass? Still, they were impressed with the progress, and more importantly the potential, they saw in humanity. The generational march forward of knowledge and thought was a revelation to creatures that had decoupled from the freight engine of biological evolution so long ago. They reasoned that once these Earthlings had been taught how to leave their husks behind, the addition of their billions to galactic exploration would inject these efforts with a new energy . It was so rare for a species to make the leap to true sentience, let alone maintain it. So many self-destructive habits inevitably accompanied reaching this state while still trapped in physical form. Only one species in a million could do it. The beings were going to help humanity leave their millennia of conflict behind, bring a new utopia, and make the galaxy a richer place. If only they could make contact . . .
Attempts were ignored or dismissed by humans as dreams. The beings realized they would need to make contact husk to husk. Humanity, so unnecessarily reliant on their bodies' limited perception of a narrow band of the electromagnetic spectrum, would need ambassadors they could see, hear, and touch. So the beings looked for the most efficient way to have an equitable conversation with humanity.
With joy, they realized that one of humanity’s inexplicable cultural traditions made this possible! For some reason, the Earthlings preserved their old husks after the sentience inside had extinguished. Across the globe, buried slightly below the ground or encased in small structures, were millions upon millions of vessels the beings could use to pilot to population centers and begin their new friendship with the humans. They collectively made their interfaces, but the beings, so removed from these things for so long, underestimated the madness and hunger and pain that would assault them when reentering the physical world. The dead rose. The Earth died.