Actually many players were better than Federer in 2000. Federer is a late bloomer. He peaked at 23-24, which was around 2004-2005. That version of Federer was nowhere close to a prime Federer.
If you want the GOAT teenager, Borg and Nadal would probably be a better example. At young age, they were already capable of beating GOATs in their respective eras.