Is America still a 'first world' country? Not compared to Japan

Recently, someone on X.com said that Japan was the last "first world country" left on earth. I felt an instinctual agreement when I read this statement. America no longer feels very "first world" to me. Not lately.

When the three worlds concept was first invented — in 1952, during the Cold War — America was the definition of "first world."

America, most of Western Europe, Japan, Korea, and a few other prosperous nations were "stable capitalist countries with the highest literacy rates, life expectancies, and living standards."