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.
Ok. I’m gonna give an example that will be slightly wrong if we nitpick, but it will give you an idea.
Lets take the old philosophical idea “if a tree falls in a forrest and theres nobody to hear it, does it make a sound?” and modify it for this example.
“If you are not there to observe will the tree in the forest fall?”
If you are not there to observe the tree will be in all possible states. Two notable states being “it has fallen” and “it is still standing” that exist simultaneously.
If you go in to the forest and observe, one of the states will randomly become your reality according to certain probability amplitude.
You don’t necessarily have to go in to the forest to observe the tree. You can send your buddy who will then tell you the state.
As your friend is returning back from his observation, there’s actually two friends walking back to you. He is “entangled” with the tree. When he opens his mouth, one of them is randomly selected as your reality.
Entity checking the state of the tree does not have to be a living consciousness. It can be a particle, that interacts with a particle, that interacts with a particle, that interacts with you. You are not conscious of the trees state, but the information is delivered to you and for you there is now only one state for the tree.
So quantium level information is constantly delivered to you and your reality is weaving itself around you through this “decoherence”
now you see how my first two examples were false. Quantium decoherence is so much faster than you or your buddy, that you can only catch this mechanism at work on quantium level.
…and “local” basicly just means that the experiments result is true, as long as nothing can transfer information faster than light. So far nothing has.