If humans could fly without wings, we'd probably need some sort of extra organ to give us the power to fly without external help, so we might develop tails too since we need space for another organ, amirite?

If you're flying without wings, I assume you mean by using energy, which isn't about having another organ. Plus, a tail isn't the best place for an organ.

Tails aren't exactly roomy...

Wings would be so much cooler.

Fish of the air