I feel your pain .
It may take a while but it should come around to being friendly after a short adjustment.
When I get them dumped off here like that I try to put food in a small hav-a-hart trap and catch them that way.
its less stress on the kitten and less worry for you.
Are you planning on keeping this little one or taking it to a shelter?
if its indeed feral its going to take a good while after capture for it to come round to being friendly.
The last feral caught here was not tamed down untill she decided she had to have her kittens, then she was all about people. before that though she hid under the bed, in closets , even under the dressers.
The only way you really knew she was here is the cat food would disapear.
I must add, be thankfull its only a kitten they dumped out, I have come home to rabbits in cages, birds in cages, snakes in cardboard boxes,lizards in tanks, all on my front step.
life on a highway is never fun to say the least.
all it takes is one idiot friend to say oh so and so has snakes maybe they will take it in, or so and so has birds etc etc.
Some people are not the brightest bulbs int he package and if they can dump it on some one for free, they certainly are not about to take it to a Humane $ociety where they have to pay to dump it.
JMHO not meaness meant.