I'm going to continue to die on this hill: American cheese slices typically have cheddar cheese as the very first ingredient. They are made of real cheese, dairy, and an emulsifier. Basically think of a cheese sauce with a higher melt temp but nobody seems to claim fondue is fake cheese
Are they good though? That's subjective, I think they go great on burgers, grilled cheese, and ramen. Are they plastic or use fake cheese? No. If you want to be accurate while high horsing about it you could call them watered down congealed cheese though
Edit to add: the individually wrapped ones are an ecological nightmare. The deli deluxe ones are higher quality, not individually wrapped, and don't even cost that much more. Or just buy not Kraft they don't need the money anyway and other companies make American cheese slices too. You can even find emulsified cheese slices for other types of cheeses if you want variety on your burgers and grilled cheese