That’s only the first couple specimens, though. All the subsequent humans were created by other humans, per Dave Barry, “using simple tools you probably have around the house.”
I’m not sure what you mean by “heaviest by volume”, but a block of 1,000 kilograms of gold wouldn’t be that big volume-wise. Gold has a density of 19.3 grammes per cubic centimetre, so that would just be a cube 37 centimetres, or 15 inches, long on each side (assuming that it’s pure 24 carat gold). And gold is not the heaviest metal used on a larger scale.
Although the title says “thing,” the OP actually asks for a “single structure.”
These certainly don’t qualify as a structure, nor could they even be considered a single “thing.” At best they are a category of things.
If you want to account for weight vs sprawlyness, you could mathematically weigh the object like this.
Pick a volume at the “center”. It weighs X. Pick another volume that is distance Y from the center. It weighs Z. Take 1/Y multiply that by Z and add to X.
Repeat for all volume elements of the structure. Add up all the numbers. Biggest sum wins.
BTW I aint digging up all the data to do this.
Kinda weird. Also gives units of kg/m, which also seems weird to me.
I propose a tweak- multiply result by shortest radius. Gets you back to mass, and gives full credit to big blocky things.
Actually, I propose we figure out how to get all the spaghetti things out of the running entirely.
Weight is really only of interest when you talk about moving the object. For anything that rests on the ground or is designed to be stationary - the mass is fairly immaterial. The individual components (bricks etc) - yes, it’s important how much they weigh because they have to be transported.
I guess the largest man-made objects ever made that moved would be ships - or possibly Oil platforms.