If the Church of Jesus Christ of Latter-day Saints is neither Catholic nor Protestant then what authority is their Church based upon

I realise there are some significant theological differences between LDS, Catholicism and Protestantism, mainly to do with the Trinity and the person of Jesus Christ. LDS doctrine recognizes Jehovah as the pre-mortal name of Jesus, who was created as a spirit son, before coming to earth as God the Son incarnate. This official [LDS article](https://www.churchofjesuschrist.org/study/ensign/1988/03/comparing-lds-beliefs-with-first-century-christianity?lang=eng) says that after the deaths of Jesus Christ and the Apostles apostasy became widespread and “lasted until Heavenly Father and His Beloved Son appeared to Joseph Smith in 1820 and initiated the restoration of the fulness of the gospel.” I understand that the Church does not accept various creeds from the fourth and fifth centuries A.D. and that those creeds do not reflect the thinking or beliefs of “the New Testament church”. From this I can only conclude that they are neither Catholic nor Protestant. What then is the foundation for this “New Testament church”? Is it based on the New Testament of the Holy Bible, or is it based on other sources? If it is based on other sources, please name them. Edit: Please note I want the official LDS answer to this question, especially as to the basis of their "New Testament Church".