Why is the whole world afraid of the USA?

Nothing of the sort . Recently US has been defeated in Afghanistan ans announced pull out

Who said they were?

false

Toddler with a gun.

Unpredictability and nuclear weapons are a bad combination.

Gay Jussie Smollett told them that we're racist.

Because we have our finger in every pie. We bully our allies and attack our opponents and kill a lot of them indiscriminately. And we have president who's like an impulsive little kid and doesn't think things out before he speaks or acts. So we're in a position to make a lot of trouble in the world, for other nations as well as ourselves.

Probably because the US military is occupying the entire planet right now with its military stationed in over 150 foreign countries, plus it has an enormously long history of trying to overthrow the governments of anyone it dislikes. Libya, Afghanistan, Iraq, Iran, Guatemala, Chile, Cuba, Nicaragua, Venezuela, Honduras, Syria, the list goes on. Gotta stay on US's good side or they'll come after you next.

The UK isn't. We're best mates.

Trump.