Is the statement that what is meant by the verse in Surat An-Nahl, "And when We substitute a verse in place of a verse," are the cosmic verses and not the legislative ones correct, especially since the verse is Makkan and there was no abrogation of rulings in Mecca? And is there a reason for the revelation of this verse that removes the ambiguity?

The verse clarifies that abrogation (naskh) is the replacement of one verse with another. Imam Al-Shafi'i used this as an argument that the Qur'an can only be abrogated by the Qur'an, and that the Sunnah cannot abrogate the Qur'an. Abrogation was rare in the Meccan period. An example of this is the abrogation of the initial verses of Surah Al-Muzzammil, which enjoined the night vigil, by the verse of alleviation at the end of theurah. The reason for the revelation of the verse was the statement of the polytheists that Muhammad commands then forbids, and that the Qur'an contradicts itself. So, the verse was revealed in response to them, clarifying that Allah knows best what He reveals in terms of abrogating and abrogated verses, and that abrogation can involve abrogating both the ruling and the recitation, or the ruling while the recitation remains, all for a wisdom known to Allah.