What is the validity of the statement of those who believe that Allah Almighty created the earth and mankind in honor of Prophet Muhammad (peace be upon him), and what is the ruling of Islam on this belief, and what is the role of the Muslim regarding that?

What that person said is incorrect, and it is likely based on fabricated hadiths such as: "Were it not for you, I would not have created the celestial spheres," and "Were it not for you, I would not have created Paradise, and were it not for you, I would not have created Hellfire." Many scholars have ruled these hadiths to be fabricated. The one who holds this belief is excused due to their ignorance, but they must be warned of the seriousness of the matter and that it is impermissible to persist in this belief or to teach it to people.