From my old A Picture Book of Idioms in Five Languages (1993):
He/she doesn’t snatch stars from the sky. – Russian version (in English translation)
He didn’t invent powder. – French, Spanish, Russian,…
He is not a great torch-bearer. – German
He won’t set the Thames on fire. - English
This English saying is obviously rises curiosity – why do you say it so – referring to the impossible event?
(Or maybe, ‘set on fire’ is used here in some indirect sense – in particularly, I saw old English pictures with great national celebrations (or grief for actually great persons, like Lord Nelson…) and the Thames on them can actually be viewed as being ‘on fire’.