Who was the first to introduce handshaking, speak Arabic, manufacture shields, and author the book "Kitab al-Kaba'ir" (Book of Major Sins)?

We apologize for not answering competition questions, as this affects the site and workflow, and because most of these questions do not entail a practical legal ruling. As for the first question, the people of Yemen were the first to introduce handshaking, as it was narrated by Anas, may Allah be pleased with him, that the Messenger of Allah, peace and blessings be upon him, said: "The people of Yemen have come to you, and they are the first to introduce handshaking."