So in Star Wars totally takes place in the past in a galaxy that isn't ours. But in our same universe, based on the clarification that it's a different galaxy.

Halo Humans entered the scene when the primodials became the flood and fled into deep space to escape the forerunners usurping them. Some time later (a long enough time that the primordials were all but forgotten from history) A large, primarily human, army shows up and start wrecking forruner planets leading to all of the events of the pre-halo forruner/human/covenant stuff.

But that means that humans from some other galaxy were advanced enough to cover interstellar travel. Tech in Star Wars is hella advanced and has been around for as long as Star Wars history has been written (unless there's somehow pre KOTOR stuff)

Some aliens in Halo and Star Wars are truely alien like Dexter Jester and the Sangheli, but the Halo live action stuff with Locke shows that "humans with makeup" aliens also exist within the Halo universe too.

The Didact annihilated the humans and devolved them as a joke, so Star Wars never getting mentioned makes sense.

Also, the force being a thing in halo would be neat: AI from the UNSC are way different than Star War droids, but force rules mean that they're both just as alive as people are.

Is master chief a skywalker as well as the guy who has the iso didact geas? Was sgt. johnson a midichlorian baby?(yes)

So yeah real life takes place between Star Wars and halo.