I noticed that in my hand the index and middle finger are aligned in one direction and the next two fingers somewhat in the opposite direction. My question is, why are our fingers aligned in that way? Moreover, is it of any evolutionary significance?
This is normal, and the effect is accentuated dramatically if you pretend to be holding an imaginary round object (somewhat smaller than a baseball, for instance.) The fingertips will all approximately point towards the very end of the thumb.
(See upper right image.) If the stone were smaller, the effect would be more visible.)
This orientation of the fingers makes the hand and fingers extremely versatile, being able to grasp and manipulate objects of a wide variety of shapes.
It also allows fine manipulation of thumb and fingers. Touching each fingertip to the tip of the thumb quickly shows the same effect - the fingertips approximately align with the thumb. If they didn't align this way, we would lose some of our very fine (as in requiring great precision, not as in quality) motor skills.
I'm not going to hypothesize on why the hand evolved the way it did; it's very efficient and that seems reason enough.
Observation: The bend in the fingers gives the straight hand a more compact appearance so that we can actually tightly close the gaps between the fingers.
Hypothesis: Without the bend small gaps would remain between the tip and the first joint of the fingers unless we press the fingers together with force. Not having this gap could protect the fingers from injury while walking or running through tight underbrush because the likelyhood of entangling the fingers in some vine or branch is lower. Also, being able to compact the hand may help us to easier scoop up water with our hands.
(yes my hand show the same slight bend in the fingers)