Very simple images galleries

I can’t believe this is as hard as it seems.

I have a page that I want to show different sets of images on.

For example… December Pics; January Pics, etc.

All I want is a thumbnail for each set of pics that can be clicked on, then a lightbox pops up and one can scroll through those pics.

I don’t want to go through a whole media library thing with checked boxes and featured images and all of that.

Every month, when a new set of pics are sent to me, I just want to be able to display them on this particular page in this format.