when we're a part of a world which is too complex for us to fully understand?

Sounds like a skill issue. The obvious answer would be "get good".

Like, look, people talk all the time about how the economy, or the human body, or what have you, is just too darn complex for one human to fully understand. But, like... humans have on the order of 30k genes. The functions of many of those have not yet been sorted out, but once they are all sorted, that's not an intractable number of functional chemical species for a single human to understand well enough to grasp the whole picture. Especially since so many of them are part of multistep modular synthesis pathways, or modular signalling circuits, or some kind of standard pattern, so whole chunks can be understood at once.

Or, the economy. There's a decently large number of functionally distinct kinds of economic actors, but like... not that many. It's not like one needs to know the particulars of each different hair salon or small trucking firm in order to basically understand the entire economy. There's only so many importantly-different types of business, and it sure seems like a human could basically understand all of them well enough to grasp the whole picture.

Of course one would need to create an entirely different kind of education program, in some cases figure out currently-unknown things (like e.g. function of some genes), and then spend several years of study, in order to understand these things. But it does not seem intractable in principle.