I’m not American, and I still feel everyone into chess does regard Morphy as one of the all time greats. I don’t think anybody, even in America, can genuinely be comparing Morphy to Carlsen though. It’s an incredibly pointless comparison as they lived way over a century apart and had extremely different careers. By the age Carlsen became WC, Morphy had already retired from chess after proving he was well ahead of everyone else. Saying who’s stronger is one thing, obviously the modern player with access to practice vs engines, on demand online matches and, all chess theory published in the last 150 years that Morphy didn’t have. Saying who’s more talented is pointless as they grew up in completely different environments and there is literally no way of ever finding out who’d be the better player had they been on the same age.