Historically the list is huge.
At 22 like Rasmus and in fact many of them quite younger where already scoring in double figures in first division. It's not that uncommon, IN FACT, Rasmus himself scored 16 last season. Also it's not that uncommon for some players to be late boomers regarding scoring and ending having extraordinary carreers as goalscorers.
Many mentioned here not being even mostly pure strikers, some not even trully extraordinary goalscorers and merely forwards/ ST/ off mids with a very good scoring output, while many having other notable atributes, not only goalscoring.
We can go over the top citing Oldies like Di Stefano, Sivori, to more recent phenoms like Ronaldo, Romario...
Or also more recent in time fellas like:
Batistuta
Raul
Crespo
RVN
Villa
Saviola
Tevez
Rooney
Falcao
Aguero
Thomas Muller
Neymar
Kane
Dybala
Julian Alvarez
...and new Gen with Wirtz and Yamal
In any case that it's not that important, some players are late boomers, some players have great starts and later fall a bit, or never recover, the majority face difficult stages and some end becoming legendary players.
The focus should be in his ACTUAL problems, some of them not even his fault at all and not trying to play Devil's advocate and use the Age card and throwing comparisons with former players, than more than help, burn the kid even more.
It just adds fuel to the fire for those that already do not like nor rate the kid.