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.
I’m pretty sure it is essentially that any propensity the macro-scale universe has for the appearance of determinism is an illusion since the fundamental scales of the universe and everything it is built on are probabilistic. Nothing built on probabilistic foundations can be deterministic. It can appear to be. In large enough samples the law of large numbers smooths all the chaos out, but that is all our world is. Mathematically smoothed chaos. We as a species have known that for a very long time, but it has only begun to permeate the social zeitgeist in recent years and there is still a lot of pushback from certain sections of society.