Praise be to Allah.
Adam (peace be upon him) was the first of the Prophets, as it says in the hadeeth narrated by Ibn Hibbaan in his Saheeh, that the Prophet (peace and blessings of Allah be upon him) was asked about Adam – was he a Prophet? He said, “Yes, a Prophet to whom Allah spoke.” But he was not a Messenger, because of the hadeeth about intercession in which it says that the people will go to Nooh and say to him, “You are the first Messenger whom Allah sent to the earth.”
This text clearly indicates that Nooh was the first of the Messengers. And Allah knows best.
Majmoo’ Fatawa Ibn ‘Uthaymeen, 1/317.
Adam the father of mankind was a Prophet, so he was the first of the Prophets.