[oh_fiddlesticks]

>technological advances are permanent that have long term impacts

That's not necessarily true, look at the clockwork cylinder fished up from the ancient Greeks that was apparently an Olympic oriented calendar.

And.... the pyramids. Built by humans, yet the method is not well understood now, so little so in fact that aliens seems more plausible.

I would say that technological advancement is often lost to time, those are just two examples and I imagine there are countless more we don't know.