Is there any idea that is accepted worldwide?

Christianity.

Money.

There are various forms of it, but every place has trade tokens of some sort in addition to barter.

The concept of counting.

Even some animals are able to count accurately for small numbers. Crows are good up to 5 objects at least.

Gravity, there's a shiny thing in the sky, lots of little dots up there to. Also, if you don't make rules to stop them, people everywhere will do stupid things. Food good, plagues bad, incest bad, disobedient kids bad, and if big guy hits little guy, big guy gets whatever he wants. Mostly just anything that's easily observed in everyday life.

Most scientific theories are accepted worldwide. (atoms, germs, gravity, etc.)

There is a big, hot ball of light in the sky. Actually, it's a mass reaction of gases, but you know what I mean.

Cats are smaller than earth, coarse that is a fact... but still, no cat is larger than the earth, not by a long shot.

That the sun gives us life? (Technically, this is both scientifically true, and believed worldwide as the Sun god is the predominant god in almost all polytheistic religions)

Doubtful.

Gravity exists.

You need some sort of food to keep you alive