Is it obligatory to smash man-made statues, and does the same ruling apply to the artifacts of previous nations (such as the Pharaohs)? And why did Amr ibn al-Aas not touch the Egyptian antiquities? And does the ruling differ based on the purpose of these statues (for worship or not)?

Making three-dimensional statues is forbidden by shari consensus among scholars. What has been made of them must be broken up so that it no longer retains the form of a statue. This applies equally to what is worshipped and what is not worshipped, and to what is old and new. This is indicated by the hadith (definition) in Sahih (definition) Muslim: "Do not leave any statue but that you efface it," and the hadith of Jibreel, in which he commanded that the head of the statue be cut off so that it would become like the shape of a tree, and that the curtain containing statues be cut up to make two pillows that would be trodden upon, and that the dog be expelled.