Many situations don't have a primary cause. There's no rule in the universe that says physical objects can always be decomposed into simple systems with a hiera

Many situations don't have a primary cause. There's no rule in the universe that says physical objects can always be decomposed into simple systems with a hierarchy of priorities. If I break my leg and have COVID, I'm not going to be better until both of those problems are fixed and neither has any bearing on the other. There is no primary cause. There may be different levels of urgency, but some problems in the real world are just intrinsically messy and complex.