system
Given the following post, respond as if you're commenting on Reddit:
human
[MCU:GotG] Why is Earth left alone?

Interstellar travel is a casual thing, where smugglers, pirates, and wanna-be galactic overloads all have their own ships fully capable of interstellar travel. These ships are cheap, readily available, and capable of long distance travel in short periods of time.

Yet for some reason Earth is left more or less completely alone. Sure, there is the occasional pirate that wanders by and abducts people for snack-time, but these are isolated incidents. Why have none of these pirates stayed? Why just have one snack for one day when they could use their superior technology and firepower to claim Earth as their own private fiefdom.

Considering how much technology goes in to these ships along with the weaponry they possess, why is to stop someone from trading for Earth's resources or outright trying to conquer Earth? Earth has almost no planetary defenses to speak of. About all Earth has for orbital defenses is Tony Stark (assuming his space capable suit isn't malfunctioning and that he isn't too drunk). Anyone with a spacecraft capable of interstellar travel is also capable of dropping rocks from orbit. Simple, ordinary rocks. They'd hit with the yield of hydrogen bombs. Wipe out a few major cities with rocks from space, and the planet's remaining leadership might be willing to negotiate.

Even going the non-violent route, what is to stop an enterprising merchant with a ship from showing up, trading worthless technological baubles to piles of gold bricks or other valuable resources? To this merchant any technological items he's trading would be cheap consumer goods. But for people on Earth they'd be technology far in advance to anything that exists, and thus, they'd be worth a fortune. This merchant could trade them for anything and everything he wanted. Even if Earth's technology level isn't all that impressive, its got resources that will be useful.

It only takes one enterprising smuggler, pirate, merchant, or warlord to try to do this. Just one. Their impact would be huge. Yet for some reason Earth is completely unaware of any alien presence.

The corpses resulting from the Battle of Manhattan are one thing. They're dead, and could be explained as some sort of genetically engineered robot thing. But a living, breathing, talking alien who wants to trade a chest full of shiny baubles would instantly make the news worldwide.
gpt
Earth is kind of a galactic DMZ because it lies at an intersection of several major intergalactic empires and also at the boundary of several different dimensions, such as Asgard. Since its obviously important to a lot of different people it's treated as a sort of neutral zone, and since no one important lives there and Earth itself is of no real consequence its mostly left alone. Why bother visiting when all you'd fine is a world lacking in decent resources and full of technologically stunted savages who still think "The Internet" is super neat. Smugglers and outlaws will ocassionally "buzz" the planet for fun, spooking the locals, maybe pick up a hitchhiker and some contraband for kicks but overall there just isn't any reason for people to throw their weight around for no gain. Humans are "aware" of alien presence, we just don't have real contact with them.

Somewhat ironically, for a planet of no importance Earth tends to be at the center of a lot of important events.