What if the world was flat, like a disc. A discworld, so to say. And it is like this because the corner of the cosmos it floats through is just a bit more absurd than regular reality.

Other way around. If your fantasy / sci-fi novel does not sell well, rebrand it as a new groundbreaking “history”. Include how it gets ridiculed by main stream science that does maliciously ignore all the evidence.

You have instantly gained a huge, uncritical customer and fan base.

Edited a few typos.

I am very certain that most animals can get airborne, even for prolonged periods of time,when reaching high enough speed. The trick lies in accelerating them to sufficient speed. Safe landing and deceleration can also pose a problem.