Which others? The majority opinion among Islamic genealogists (as far as I remember) was what I stated. There were Arabs living in the Arabian peninsula long before the birth of prophet Ismail (AS). Who exactly did he marry into and learn the language from if that was not the case? The chinese? Australian Aborigines? It has been proven by secular academics that the Arabic language existed long before the time prophet Ibrahim (AS) was believed to have existed. There's simply no other way to resolve these contradictions other than supporting the majority opinion held by Islamic scholars of the classification between the groups within the Arabs.
FYI: I'm not the one who invented that term and its application, but that's how it has historically been used by the classical scholars of Islam who specialize in this field.
We all know Arabs existed before the Prophet Ismail (AS), these include the tribes of 'Ad, Thamud, etc. Some of the scholars are of the opinion that the first person to speak Arabic was Noah (AS) whilst others say Ibrahim (AS) and some say Adam (AS).
The Prophet Ismail (AS) married in to Bani Jurhum who were said to be Qahtaanis. It could be that the Kahlan branch of Qahtaan are in fact from the offsprings of Ismail (AS) whilst the Himyar and Jurhum are العرب العاربة
Sahih Bukhari
Volume 4, Book 52, Number 148:
Narrated Salama bin Al-Akwa:
The Prophet passed by some people of the tribe of Bani Aslam who were practicing archery. The Prophet said, "O Bani Ismail ! Practice archery as your father Isma'il was a great archer. Keep on throwing arrows and I am with Bani so-and-so." So one of the parties ceased throwing. Allah's Apostle said, "Why do you not throw?" They replied, "How should we throw while you are with them (i.e. on their side)?" On that the Prophet said, "Throw, and I am with all of you."
Bani Aslam were said to be related to Khazraj who are descendants of Kahlan. Since it's confirmed that they are the offsprings of Ismail (AS), the same can be said about the rest of the tribes from Kahlan.
Thus it's possible that a large percentage of Arabs from Qahtan who are believed to be العرب العاربة are in fact العرب المستعربة