In my aliens-as-religion post a couple weeks back I mentioned the way some people undersell human ingenuity. For example, there are those who believe aliens must have built the pyramids because they can’t fathom the primitive Egyptians being capable of assembling the blocks.
Then along come people like Wally Wallington. He’s rebuilding Stonehenge by hand, using nothing more than wood and rocks. Who’s to say the same or similar principles weren’t used to build the pyramids? Just because we can’t figure it out doesn’t mean they couldn’t.
Lack of evidence is not evidence itself.
In more modern times, some propeller heads also figured out how to better convert radiation to electricity using nanomaterials. This, too, is something that would have been unfathomable a century ago, and something we couldn’t yet pull off in the 1960’s. That doesn’t automatically mean we must have reverse-engineered it from Roswell wreckage.
Yes, people as a whole are stupid and ignorant. However, it only takes a few visionaries to come up with something great.