Where do the spacefaring humans of the MCU come from?

Question

Update: I just re-watched The Avengers (the 2012 movie). At the very beginning, we see The Other telling Thanos (who we can't see yet - we only see him in the after-credits scene) that the Tesseract is located on "a human world." Not "the human world," "a human world" - implying that there are other human worlds besides Earth.

This means that the accepted answer to this question is no longer valid, although I will keep it checked until a new answer is provided.

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In Guardians of the Galaxy and Vol. 2, we run into several humans who seem to have been in space for quite a while, prior to the events of the Infinity Saga (i.e. before 1995).

We know how Peter Quill ended up in space. But there is also Stakar Ogord and Aleta Ogord, who as far as I can tell are humans, and also seem to have been in space for quite a while. Moreover, most aliens seem to be familiar with humans, even though according to the main story-line, very few humans had left the solar system or had contact with extraterrestrials prior to the events of The Avengers (2012).

Have there always been "older" space faring humans in the MCU?

Answer 1

The only known space faring humans we've seen in the MCU thus far are Peter Quill, who is only half human, and Carol Danvers, who has special powers from the Tesseract. The only others are the Avengers from Avengers: Infinity War onwards who went to space to fight Thanos. Every other "human" we see are actually humanoid or just look like a human rather than actually being human.

As was mentioned in the comments Stakar and Aleta Ogord are in this latter category, they are humanoid but not actually human. Again as said in the comments their origins aren't clear but the MCU wiki page for Aleta mentions she is Arcturan like the comics, though that information probably comes from the comics.

Coming down to how people were familiar with humans there are a few possible reasons:

• Carol was quite a force and she worked away around the universe helping the Skrull and others in need and presumably also helped fight against the Kree. Word of a human doing such good deeds probably travelled quite far so would have made people aware of Earth.

• As we see in Captain Marvel there is actually a jump point at Earth so someone would have had to build it there. Going from having a jump point there to people knowing about Earth doesn't seem to be a huge stretch.

• The Kree themselves have been to Earth a few times over the years, Mar-Vell was there working on the light speed engine, Yon-Rogg had gone there to find Mar-Vell and we also learn that Minn-Erva has been there before (with Yonn-Rogg if I remember correctly). The Kree even have a designation for Earth: C-53. Again it's not a stretch to go from they've been to Earth over the years to others have been and to others know of it.

  Carol: I'm on planet C-53.

  [...]

  Bron-Char: Have you visited C-53?

  Minn-Erva: Once, it's a real shithole.

  _{Captain Marvel}

• The Ravagers seemed to know of Earth before picking Peter up but they were ordered to do so from Ego so it's possible they just found out from him if they hadn't heard of it before.

  Yondu Udonta: When I picked you up on Terra...

  Peter Quill: "Picked me up."

  Yondu Udonta: ...these boys of mine wanted to eat you.

  Peter Quill: Yeah?

  Yondu Udonta: They ain’t never tasted any Terran before. I stopped ‘em. You’re alive because of me!

  _{Guardians of the Galaxy}

• As we see in the above quote other species also have a name for Earth, Terra with people from Earth being called Terrans. They had to get that name from somewhere which would again indicate they already knew.

• Post Guardians of the Galaxy people around the galaxy also started knowing about humans because of what Peter and the Guardians did. Ego even comments to this effect.

  Ego: I searched for you for so long. When I heard a man from Earth held an Infinity Stone in his hand without dying, I knew you must be the son of the woman I loved.

  _{Guardians of the Galaxy Vol. 2}