You're exactly right. A race of beings sprung up out of the mud of their home world, discovered science, space travel, faster than light travel, decided to visit a solar system and place an artificial ring around a rock in the distant outer reaches of a solar system, and then... profit?
Actually ceramic materials make the best protection against missiles like bullets or meteorites. So an advanced race of star travelers would not use metal-skinned ships, they would coat their vessels with a thick layer of porous rock. All we can see is that outer protective skin. Inside the star travelers live generation after generation patiently waiting until they find a habitable planet to take over.
And then they immediately die because life is designed for a planet, not the other way around, unless by habitable you mean a planet that is uninhabitable, artificially made habitable.
A race of beings sprung up out of the mud of their home world, discover science, space travel, decide to visit a nearby rock, and place some plastic glued to a metal pole on it, and then... profit?
If this is an artificial item - a big honking if - there's not enough known about it to draw any significant conclusions. It could be their version of a flag. It could be a relay satellite. It could be a billboard to advertise McJxrqins.
