I think there is a nuance. The Quran was revealed to the Arabs primarily to warn them of the punishment coming to destroy them if the deny the messenger of God صلى الله عليه وسلم . Then there is the second part of the Quran, since it is the final book of the religion Islam, that relates to overarching moral principles such as to be good to our parents. The story about the hypocrites trying to smear the reputations of the mothers of the believers رضي الله عنهن shows us the extent of the arrogance and stubbornness and evilness of those who denied the messenger صلى الله عليه وسلم. And we are meant to be diametrically opposite to them and respect our mothers etc. But yes the primary addressees of the Quran are the Arabs. The part of the Quran that is a Warner is of all of times though which includes ideas of revelation on the universe and morals