Some are easily explained as I too made some and got the switch. Others are far to complex to be made by humans with boards and rope. There is other evidence that these are not and cannot be man made.
I see your point.
Good forensic investigation should reveal foot prints. Even in the fall at harvest time, when I walk in a corn or wheat field, the soil between the plants is still loose enough to leave a very recognizable foot print. Also the boards should leave occasional marks in the soil.
But the big one is they have to get from the edge to the middle of the field thereby leaving a foot print trail, that’s where foot prints should be easily found.
“You’re right, Egon. No human could stack books like that.”
/Ghostbusters