There is no such thing as an apolitical organisation. That’s the definition of politics.

It is not a police, it has no coercive power. The reason is obvious if you think more than 10 seconds about how to get sovereign governments to cooperate on public health matters.

What would be your ideal organisation? One subservient to the American government? Or do you want it to be a world government above sovereign states? How do you think it would fly?

That's literally the whole point of the WHO. Leaving it would mean either a) starting a "new" version and asking all the same people to join it (which seems to be what you're suggesting; what purpose would that serve?) or b) having no forum at all for global coordination over health crises.

What do you feel an apolitical organization would look like on the world stage?

Because WHO does so much more than finding out where a disease started.