Originally Posted by capeorigins
Hmm, I think you might be in bootloader? What does it look like on your screen?
You're right! I booted into recovery, and now adb recognizes my device! I pulled all SD card contents to my PC, which includes the photos I was trying to save.
Thanks so much for the help, and sorry for being dense; your first post should have been enough to get me through this.
LG Nexus 5 - bought 11/2013
Samsung Nexus 10 - bought 11/2012
Previously owned Nexus S, Nexus 4, Nexus 7 (1st-generation), Nexus 7 (2nd-generation) and Samsung Chromebook (WiFi, 11.6")