Comment by zanny

If we could reduce the density of a person by about an order of magnitude we can start replicating bird flight on a per-person basis. Our approaches to flight are constrained in all forms by the desire to put really heavy things into the air.

Look no further than drones that can operate for quite a long while, move in any dimension fairly well, and manage some pretty ridiculous speeds for not being designed to do so all because their purpose is not to carry large complicated amounts of weight.