Well, this is the first time I've used an ADC that didn't offer 0 to 3.3V range. I didn't look closely at the LIS3DH accelerometer data sheet until I started testing the boards.

Thank you for clearing this up, Adafruit team!

https://learn.adafruit.com/adafruit-lis3dh-triple-axis-accelerometer-breakout/arduino

But the good news is that all of the hardware works! I'm excited to see what possibilities are unleashed with the 3-axis accelerometer as part of the user interface.