the first words on screen are "a long time ago, in a galaxy far, far away"
so it's definitely set in the distant past.
people in the Star Wars galaxy don't know which planet humans are native to, so while they may be native to that galaxy, there's equally little evidence against a time-travel event, and humans there are Earth humans from our future who went tens of thousands of years back in time as well as moving to a far away galaxy. This could also help explain why humans there use Latin and Greek letters so much.