The Ant and Weight
We are often told that an ant can lift 50 times its own weight and stand pressures on its body of 5,000 their own weight.
The top human lift is around 3 times their weight if in good condition and trained and can stand pressures maybe 50 times.
The average ant weighs around 0.005 grams and the average human around 70Kg.
Of course, we have the much-quoted comparison of that the ant, if they were the size of a human could lift as much as 10 tonnes, but the fact of the matter is in an ant’s lightness. An ant the size of a human could not stand up and would probably die from its own weight, let alone lift even a kilogram, and a human, if they were the size of an ant would probably be able to lift maybe 30 times their own weight.
You get similar comparisons in scale for things like grasshoppers etc.
Body construction is the key factor in size, even larger structures being available if they are in a buoyant medium such as water, but then it comes down to acute streamlining and a stylised body version compared to similar land creatures. When you are considering the air, you have alternative constraints of weight and streamlining, usually meaning a lot of hollow tube type constructions. Tubes, on tubes, on tubes. If we really ever get practical electrical air travel the batteries by necessity will probably be totally tubular.
Another example of scale differences and limits is falling onto a hard surface. An insect can fall from 100 or even a thousand times its own length without even noticing it. Drop a human from a height 5 times their length and they usually have major injuries.
The scale is mainly affected by volume, air resistance and stopping g-force, a cube of 100x100x100cm having as much overall mass as 1000 times the size of 10x10x10cm, a 1/10th of the height, but a 1000 times mass has a massive impact in comparison.