I press Shift+A, choose image, then I see the menu for browsing images. So if I select several pictures and add them, Blender will join them in one video-stripe, but I want to avoid that. I want to add a range of separate images at a time to work with them in the VSE.
Add images as usual strip and then use Separate Images to make each image as separate strip.
Y Converts the strip into multiple strips, one strip for each frame. Very useful for slide shows and other cases where you want to bring in a set on non-continuous images.
With strip selected press Y (or open Strip > Separate Images) and choose how long (in frames) each resulting strip should be.
Then you can grab resulting strips as desired.