OK, let's ignore the analogy.

Everywhere else I've seen, arrows (or directed edges in a graph) point as
SOURCE -> TARGET
SOURCE -> DESTINATION
(TARGET and DESTINATION are synonymous in this context)
An example from math: https://en.wikipedia.org/wiki/Category_(mathematics)#Definition

ln has two arguments, LINKNAME and TARGET, so it's implied that
LINKNAME -> TARGET
In fact that's exactly what you see visually when you run ls -l

In os.symlink, however, you have
SRC <- DST
which is weird. I agree that this weirdness is explained in grammatically correct English.

Just because it's the first argument, we shouldn't call it src. The arg ordering is already confusing enough https://unix.stackexchange.com/questions/541795/tips-for-remembering-the-order-of-parameters-for-ln