You can change a Google Drive image link to a download link by swapping for (just use a replace all tool, I'm fond of TextMechanic's simple, free, online Find and Replace but Notepad find and replace will do the trick).
I'm a user of Google Drive and as you say it's just a matter of getting the download link. An example on my drive is
for the share link, or
for the edit link. The download link is
as described in this article.
So it's simply a matter of find and replace on
and finding and replacing
(nothing i.e. deleting them)
Once you've done that you can download a list of files in a number of ways, but if you want to stay in the browser I've written a Chrome extension called TabSave to do just that - there's an option to use a manual list for downloading (it also allows downloading files in every tab of a window).
You can just paste in from your list of edited URLs and they'll download. Very lightweight and you don't need to worry about dodgy installation of these one-hit wonder freeware programs. All the code is open source on GitHub (link in the webstore description).