I think the honest way to express what you've said here would be to say there is no such thing as full "Understanding", or certainty, we actually don't know 100% of anything with certainty, nature itself is uncertain, we can't predict the future, its a profit driven instinct to try to encapsulate all knowledge into specialisations - that was all about commoditisation. We have to always accept reductionist arguments, but we should at least acknowledge the limitations of what we know. It would be impossible to try to express the whole physical system, such an explanation would require infinite time, and infinite energy.

The drive to abstraction is a practical way of expressing just the important parts of whatever it is we are trying to describe, and it looks like Sagan did a pretty good job of that.

I would be wary of getting too lost in the details, when we do that, we can often miss the biggest fish, like mathematically positive powered Ai, which is an emergent property with deity level intelligence.

I bet you've missed that so far.