One idea wandering around the cobwebby nooks and crannies of my mind concerns our incomplete knowledge of the material world. It's only an idle weekend thought, you can't draw useful conclusions from it, but it goes like this.
Firstly, the physical universe has no internal boundaries. No physical part of it is as far as we know, wholly isolated from everything else with the possible exception of black holes. So if we try to understand absolutely everything about some part of the universe, say a leaf for example, how would that be possible? In other words, how would we set boundaries to the leaf so we may know everything there is to know about our special chosen leaf?
For example, we'd have to know all about the biochemical and genetic structure of our leaf, how its cells function, how photosynthesis happens, where its genetic code came from, how it evolved and what it does in relation to its parent plant.
Then we might move on from those mind-boggling complexities to the leaf's component atoms, including where those atoms came from to make molecules of leaf and how they are exchanged with the environment as nutrients.
Next we'd have to know all about the subatomic particles within those leaf atoms, the forces holding them together, the radiation they absorb and emit, their role in photosynthesis. We'd even have to know how our leaf was affected by gravity, so we'd have to know for sure what gravity is.
But of course all this endless, mind-numbing detail takes us beyond the leaf into the big wide universe because there is no place to stop, no boundary where the leaf ends and the rest of the universe begins. I won't take this too far because it's merely an armchair notion, but it surely suggests our knowledge is necessarily incomplete.
In other words, there is only incomplete knowledge or omniscience, but the incompleteness applies to everything. Our knowledge of every single thing we can think of must be incomplete, however small it is, however simple. Otherwise, we'd have picked the knot and the universe would unravel like a ball of string so we'd know everything.