system
Given the following post, respond as if you're commenting on Reddit:
human
Why is the computer arrow slightly tilted?

Or why is the hand not tilted?
gpt
The up-and-to-the-left arrow cursor originated at Xerox PARC in the 1970s on the Alto computer. The reason the left edge of the arrow is vertical is simple: it displays as a straight line without any jaggies. An arrow pointing straight up was found to be harder on the eye due to the jagged diagonals. That arrow shape has been used ever since. 

Oh, and why point the arrow up and left? Simply because the origin of the cursor bitmap is in the upper left. This put the cursor's hot spot conveniently at (0, 0), saving the mouse tracking subroutine a couple of compute cycles by not having to calculate x and y offsets.

ELI5 - It made more sense/looked better on old computers. We just haven't changed it because it'd be weird.