I am amused by how an outrageous claim will be made, later disproven, then dismissed to go onto the next outrageous claim.
The whole notion of moving enormous rocks that required alien intervention was debunked when scientists discovered enough evidence to understand how Stonehenge components were hauled around. Some enterprising guy came up with a very clever pulley and lever system to move rocks of the same size, weight, and proportion without any motorized assistance. Despite people living in a time considered primitive by our standards, there were some intensely impressive achievements of mathematical understanding made that enabled certain groups to accomplish feats that would leave most human beings today baffled in amazement.
But "Ancient Aliens" is such a fun and compelling alternative!
Frankly, unless there is truly some kind of "space folding" technique possible with the right amount of power and device orchestration, travel between worlds is sadly linear and VERY long term. Which means that considering any sentient aliens being able to visit us is just outright impossible. We're on the periphery of the Milky Way galaxy. There's far more activity going on near the core to keep sentient beings busy than to wander off into the vast void of multi-generational space time on a mostly doomed quest to see if there's anybody living out on the periphery. Also, considering the time and distance problem, the fact that our lives have been so brief on this planet, we're too far away for anybody to even realize that sentient life has formed here.