Even if there are aliens, and humans do sometimes gain data showing such, if the aliens are sufficiently advanced and don’t want to be found, I would not be surprised if they selectively took away our conclusive data but left behind the stuff that’s already indistinguishable from noise. Kinda like how we take our trash with us after hiking and camping, but don’t worry too much in most places about our footprints or the microscopic bits of material our gear and bodies leave behind.
Even if there are aliens, and humans do sometimes gain data showing such, if the aliens are sufficiently advanced and don’t want to be found, I would not be surprised if they selectively took away our conclusive data but left behind the stuff that’s already indistinguishable from noise. Kinda like how we take our trash with us after hiking and camping, but don’t worry too much in most places about our footprints or the microscopic bits of material our gear and bodies leave behind.