[34:29] And We have not sent thee but as a bearer of glad tidings and a Warner, for all mankind, but most men know not.
The Holy Quran Arabic text with Translation in English text and Search Engine - Al Islam Online
Thanks for finding the verse. It may denote that the Revelation of Muhammad was for all mankind, however, in my view some questions rises as for the Translations and interpretations.
In the verse, the Word, لنَّاسِ is translated as for people.
But which people? Maybe Jews and Christians, and not for example Buddhist or Hindus??
The word that may mean "All" in the verse is كَافَّةً. But this word has multiple meaning, and does not necessarily mean "All". Here are the list of the verses which the word كَافَّةً occurs:
(2:208:7) kāffatan completely يَا أَيُّهَا الَّذِينَ آمَنُوا ادْخُلُوا فِي السِّلْمِ كَافَّةً
(9:36:28) kāffatan all together وَقَاتِلُوا الْمُشْرِكِينَ كَافَّةً
(9:36:31) kāffatan all together كَمَا يُقَاتِلُونَكُمْ كَافَّةً
(9:122:5) kāffatan all together وَمَا كَانَ الْمُؤْمِنُونَ لِيَنْفِرُوا كَافَّةً
(34:28:4) kāffatan comprehensively وَمَا أَرْسَلْنَاكَ إِلَّا كَافَّةً لِلنَّاسِ بَشِيرًا وَنَذِيرًا
The Quranic Arabic Corpus - Quran Search
And some other translators, have translated that word as "perfectly"
So, do you think it could be that the verse is saying, "Muhammad is sent for people as "Perfect" Warner...."??
Because there is a better word that Quran uses which means "All", and that word is كُلِّ.
لِكُلِّ لنَّاسِ means for all people. But كَافَّةً لِلنَّاسِ can mean, perfectly for people.
Even if lets say, Muhammad was sent as a Warner and bearer of glad tidings about the Day of Judgement, why does this necessarily mean, the Sharia Law was meant to be followed by all people?