Translation:I had never thought myself famous until that moment.
"I never had thought myself famous until that moment" should also be accepted, no? I reported it.
"Never" should be before main verb according to English grammar, shouldn't it?
That's usually more natural, but I've never known it to be a set rule. It can be a subtle way of changing tone, especially in spoken English. As a copyeditor, I would probably change it only if the word order sounded unnatural or made the meaning ambiguous. Perhaps it sounds more unnatural to others than it does to me?
Displacing the adverb of frequency from the usual position - between the auxiliary and the main verb - can make the statement seem more emphatic.
I had never thought myself famous until that moment.
I never had thought myself famous until that moment!
Corpus of English - ngrams: https://tinyurl.com/ya7hwt8q
Same difference to me, to be honest. Maybe it's where you put the stress on the sentence that changes the meaning slightly.
"I had never thought of myself as famous until that moment" - to my ears this is the most correct English grammatically.