To get from his cave in Natchez to his uncle’s cave in Mobile.
Obviously.
I would nominate lead from tetra ethyl lead as the most ubiquitous man made, easily recognizable object (albeit under a spectrometer) on earth with one inventor.
It’s so ubiquitous that for lead dating, you’ll have to go deep into the earth or rely on meteorites/
Philip Vaughan invented the ball bearing in 1794. Just about every moving object we use has them - whether we move it manually, or it moves by itself.
I like that one. Some of the others suggested might well be more ubiquitous, but usually as part of something else, and an item the vast majority of people will never see in their lifetimes, let alone every day.
Also now I know the name of that type of chair.
I can’t believe I still get to offer
King Camp Gillette, inventor of the safety razor blade.
Or his mentor William Painter who invented the Crown cork
I think the paper clip, invented by Johan Vaaler has to be in consideration, it’s an iconic design recognized the world over. Btw, great OP question.