There are different options at the top of the import dialog. One of them is to copy and another one is to copy as DNG. Look at the options along the top of the import dialogue and choose the right one.
I didn't have any images to import. But you can see the options, and the one on the left is probably the one that you have selected.
Thank you Jim.
Quickly….I want them to stay as RAW (NEF). Do I just click copy? Never had to do this before and the files were always .NEF. Then two days ago I was unable to import any files (said they could not be read). A few hours later I tried again and they could be read, but the option had been changed (not by me) to convert to DNG. This is Lightroom 6 (stand alone). Should I be doing any updating of LR6?
You would probably want to make sure you are using Lightroom 6 .5. However, I doubt very much that updating would have any impact on the options chosen in the import dialog. Whenever you receive a message that files cannot be read, that usually means that the files cannot be written to the specified designation. This has to do with user permissions of the drive or folder that you are trying to copy the images to. But changing to "Copy as DNG" should have no impact on that. And, yes, you would just click "Copy" to copy your images as the original NEF files.