For me it is the fact that our blood contains iron. I earlier used to believe the word stood for some ‘organic element’ since I couldn’t accept we had metal flowing through our supposed carbon-based bodies, till I realized that is where the taste and smell of blood comes from.
It doesn’t. Gravity is caused by mass not spin. The planet’s rotation about it’s own axis will create a centrifugal effect that offsets gravity, but the effect is negligible for anything rotating as slow as planets.