The UNSC's tech is outdated for being 500 years in the future. Extremely outdated.
Humans now are already developing warp drives, active camouflage, exoskeletons, hydrogen fuel cell cars, nuclear reactors with zero emission, and more! While we certainly aren't even close to creating a 3 mile long super-ship, we should be far beyond that in, I dare say, 300 years! Maybe even less! Even a Spartan by then would be unimpressive!
For 500 years into the future, I'd be willing to wager that the Covenant would be little more than a bug to us. A nuisance.
By then, I would assume humanity would have things like... I've actually got nothing. What we could do by then is unthinkable. Maybe we can make stars go supernovae?
[i]What do you think?[/i]
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The Halo universe was also created almost 12 years ago when we didn't have all of the things you listed. I'm sure that if the universe was created today, they would be way more advanced.