Causality – the problem of the day

Hello Rabbi,
Perhaps this is a question of ignorance, but "not the shy one learned": What was David Hume's fundamental problem with causality? It is true that we do not observe it, and it is also impossible to prove it with logical proof, but is there not a very, very high level of probability here (to the point where no sane person would consider the other side) that if the sun has shone until now, it will continue to shine from now on?
I have no problem understanding that Yom did not seek to 'know' whether causality exists, but rather to 'understand' how this concept was created. But my introductory philosophy books describe it as if because of Yom all of science felt threatened until Kant came and saved it.