A lot of stationary: paper clips, staples, pencils, sticky notes

A lot of toys: yoyo, slinky, hula hoop, Play-Doh, crayons

Packaging: cardboard box, plastic bottles, plastic bottles with the lid on the bottom, aluminum cans

You use inventions all the time that you could probably just build from home now that you know what they are. But there's nothing that says you/we are already aware of every simple invention. Just think about all the simple, yet revolutionary ideas no one has thought of yet....and if you can do that, you'll be a billionaire.

Not the person you initially asked, but a good one is Eli Whitney's cotton gin that made separating the cotton fiber from the seeds much easier. It had traditionally been done by hand, which is very time consuming. Whitney's invention greatly simplified the process and made cotton farming much more economically viable as an industry, ultimately leading to an extreme expansion in chattel slavery in the Southern United States and serving to solidify a planter aristocracy that would eventually seek to split with the United States in order to create its own slaveholding empire, triggering a Civil War that would decimate a large chunk of the country and kill three quarters of a million people.