The basic situation is that a black hole at the center of the galaxy.
is pulling in stars in a whirlpool, as the arms sweep up stars at the outer edges of the galaxy, This is continious.
Therefore there is an ongoing immigration of populations from the center towards the outer edges of the arms. Galactic Civilization exists in a wide band from the edge of the radiation whirlpool, near the black hole, outward to a point where distances become awkward.
As in any civilization "law and order" are enforced near the center, but as you approach the frontier, it begins to break down. Beyond the frontier is unknown pirate realm where anything goes. Between the two extremes lies a grey area, an area of opportunity, but high risk.

Our solar system has moved out of the pirate zone into the grey area.
Sometime in the last 500,000 Earth years.

The situation is complicated by a physics phenomona involving time travel, in and out of gravitational fields. Where the stars are to close you can't get outside of a gravitational field enough to make spacetime jumps.
This is where we become important to the galaxy. The time jump phenomona Inside our gravity field allows a ship to move to the far side of the galaxy and then out of the gravity field and back to the present. An instantaneous transfer from one side of the galaxy to the other. This phenomona only exists in the "grey zone".

Apparently there are timejump nodes of importance on earth at specific points in our history, these are the periods of history where technology made extreme irrational advances. Such as the pyramids, and the last 100 years. Inbetween are the "dark ages" where we are forgotten and left to the mercy of the pirate realm. Luckily they are relatively few. We see their effects in history as the "snake in the garden of eden", "the medieval dragons", etc. Mostly they are of a reptilian bipedal species with extreme hypnotic powers.

Some others that stayed for their own reasons:
The Aryans of Thule
and their human recruits, the Illuminati.
New arrivals include the "Big nosed greys",
I think these are constructed androids.
These are the ones which do the abductions, and Animal mutilations.
And their Human recruits,
The Jason society.
Their are many more bases of other species, usually they are located in volcanic tubes such as found at Mt Shasta Ca.
Usually their is a group of human "believers" or converts which supply them with "things or subjects".

Consider potential viewpoints:
Ours and theirs, the range goes from ours of
the original "bug eyed monster" a snail,
is it edible?
To do we become slaves, as has happened in the past,
or set up an embassy and treat them as a civilized government.
Hopefully we could then enter the galaxy as equals.