Your aliens invented humans. Who knows, we may be the result of their genetic experimentation.
It eats everything that contains organic tissue
People in Mexico eat crickets and drink cactus water.
People in Japan eat roaches and algae.
People in China eat spiders, scorpions, centipedes and dogs.
People in the Netherlands eat horses.
People in Spain eat squid ink.
People in Russia have even eaten a defrosted mammoth.
All those are typical foods, sometimes elevated to fine cuisine. The world's most expensive food is sturgeon roe for crying out loud.
It can survive any environment that we know life exists in on earth.
With our current technology we've been to the Marianas trench. With not so current tech we have McGyvered into the skies.
It itself is 100% guaranteed organic (not a virus)
Frame challenge. No life as we know comes even close to that.
We are mostly made of water which is inorganic, but dry a human into dust and you will find we are about 24% organic.
That said, if you meant 100% as not being a cyborg or a construct, we fit the bill.
It follows the rules of known physics and organics
Yeah we keep trying to break them, and so far it has been them that break us.
The makers don't have any unobtanium
It's cool, we're not made of that. Nor from that.
They made the trip from Europa safe and sound and hungry
These creatures won't leave the planet
Here and there you will find a human who would love if you could fly them to the moon and let them play among the stars. The majority is very emotionally attached to the specific piece of land they've been born on, though.
We can't eliminate them. Sorry.
Humans are a hard nut to crack. We have nukes, Jesus and Chuck Norris on our side.