Exegesis of the saying of Allah the Exalted: ((Alif, Lam, Mim)) and do these composite letters have meanings?

Allah the Exalted said: This word is composed of three alphabetic letters: Alif, Lam, and Mim. So what is the meaning of these letters from which this word is composed? Many of the exegetes say: Allah knows best what He intended, and this is undoubtedly a form of politeness toward Allah (Mighty and Majestic) and refraining from what a person does not know. Some of them made them symbols for specific things, either from the names of Allah or other events, and this is not based on knowledge. Some of them said: They are alphabetic letters that have no meaning, and we do not know a meaning for them according to the requirements of the Arabic language. The Noble Qur'an was revealed in the Arabic language, and on this basis, it is our right to say that they have no meaning, based on the fact that the Qur'an is Arabic and that such composite letters have no meaning. This is the statement of Mujahid (may Allah have mercy on him), who is the imam of the Tabi'un in exegesis, and it is the statement that the evidence requires. However, the question remains: why did Allah bring them if they have no meaning according to the Arabic language? We say: It is an indication that this Noble Qur'an, which defeated you, O Arabs, did not come with anything new in speech, but rather came with what you use to compose your speech and build it upon. Your speech consists of letters: Alif, Ba, Tha, and so on. Did the Qur'an come with anything extra? No. And yet, you were unable to compose something like it; it defeated you.