With the Marshmallow OS, the default USB mode is charge only. Pull down the notification shade, tap where it says USB charging, and change it to file transfer.
also send via Bluetooth, and get a cloud service like google photos or Dropbox to have pics stored there, therefore when at PC they will be there in the cloud. better than painfully do one at a time. also just simple take pics and share to self, therefore will be on PC too.GMAIL IS MORE FRIENDLY SENDING LARGE PICS SIZES
follow tikibar1's suggestion & then drag/drop from phone to pc.
i did it the opposite way from pics on the pc into the gallery.
individual pics & albums were transferred intact.
I do not seem to have USB charging on notifications and I cannot change to file transfer...........I have the S7 Edge, I just want to get my photos onto my computer from my phone. It use to let me do that and now I can't.