It is true that a Harpy Eagle can lift more than three-quarters of its body weight while the Boeing 747 Large Cargo Freighter has a maximum take-off weight of almost double its operating empty weight (I suspect that insects can do better).

Which doesn't (automatically) mean that the 747 has worse design than the eagle. Smaller things (constructions, machines, animals) are relatively stronger than bigger things not because of their superior design, but because physics of materials is not scale invariant (unless you somehow managed to scale the size of atoms too). If you made a 1000:1 scaled copy of an ant, it wouldn't be able to lift objects twenty times heavier.