Agreed. First Cause.of the Big Bang is unknown. True Scientists would leave the cause unknown until further info becomes available.
That's not the way science generally works. You postulate "causes" then predict what should be observable if your "cause" is true. Then go look for those observables. If you find them, your "cause" is not necessarily true, but it's a better explanation than what went before. Science progress by two paths. One is an attempt to explain the anomalies in observations that do not fit with the current theory, the other is to explore "causes" of known phenomena.