I didn't say we "know" the universe is homogeneous. I said it seems to be. I said that because looking out in every direction, the same elements we know are spread rather evenly, and the temperature and background radiation as well. If the Big Bang Theory is correct, that stands to reason. This is also why I said it seems unlikely that they'd have materials unknown to us.(By "materials" I mean naturally occuring substances, made by the same elements on the periodic table.)
Comparing us to our historical peoples and comparing the people 300 years into the future to us doesn't work. Humanity lived for thousands of years with very little change until the last century, and the advent of technology and the industrial age. Also, as I stated earlier, we now rely on science, rather than superstition, so our curiosity drives us to learn and understand, as opposed to our fear keeping our heads in the sand.
It's entirely possible that we're close to reaching the limit of what's possible, technologically, at least where space travel is concerned. It may be that we can work out how to travel at near light speed, or maybe even beyond light speed, but it may require a power source that's impossible to harness.
I have no doubt there are other life forms out there, and little doubt there are intelligent species. But it may be that no matter how intelligent they are, they'll always be subject to the laws of physics that we know.