Is it true that you can compare the jump of a flea to a human jumping over an apartment building?

Answer

If you just enlarged a flea into a human, this would be true. But you can’t just do that! Scientists, mostly biologists who like math (or mathematicians who like biology) write thick books about what it means to have a large, or just a small, body. They discovered that to jump high, you can have quite long legs. There you are like a flea with your feet of half a millimeter!
Fleas have therefore found something on it: a built-in catapult. Their legs contain elastic blocks that they slowly but surely press when preparing for a jump. When the time comes, they make this block bounce back very quickly. This makes the flea shoot away – just like an arrow from a bow or a stone from a catapult.