What are people ordering now that they didn't usually order? I don't think stuff like facemasks and gloves can justify the huge difference in volumes, and amazon isn't providing the supplies for emergency rooms and hospitals (is it?).
* Many people can't/won't visit the stores that are open due to COVID-19.
* Some people are stocking up on some additional goods due to COVID-19 like bleach/masks/sanitizer.
It's pretty obvious how each one of those factors increases the demand for Amazon deliveries.
When the grocery stores ran out of tp, people started ordering from Amazon. When Amazon ran out of 2-day-delivery tp, people started ordering bidets.
People who suddenly WFH are now ordering extra supplies to do so (webcams, ethernet cables, whiteboards, privacy screens, headphones, etc). People with children out of school are ordering extra books, crafts, boardgames, videogames, etc. People SIP are now turning to Amazon for groceries and daily supplies. (Yes, grocery stores are open, but many don't want to go out if it can be at all avoided.)
In short, almost everyone who thinks of buying from Amazon is ordering something they don't usually order and/or ordering the normal items more frequently.