The problem is that you are beating your self up with
which-came-first-the-chicken-or-the-egg type thinking. The answer to
that conundrum lies in being able to step back and look at the larger
picture of evolution.

You can't figure this out going "ta duh tee dee da dum" either. All
the aspects of flow adjust simultaneously to satisfy the requirement
for energy conservation. Whenever the idea of "cause" intrudes into
your thinking squash it. Instead look for the symmetries that create
the balance that conserves energy and follow the energy flow.

You can't have a change in flow with out changes in pressure. You
can't have pressure differentials without flow (in an open system).
All of these things being discussed are just aspects of what happens
when a flow is set up in such a way that energy conservation requires
an upwards force (lift) equal to the downward pull of gravity. None
of them are "causing" any of the others. They are all caused by need
for energy to be conserved.

It is very simple and elegant once you can free your mind up from
plodding point to point and can just see the whole picture.

Why does the air speed up on top of an airfoil? Because none of the
other requirements for lift to be produced could be happening together
unless it was.

--

Roger Long