The scriptures teach us that we may be and are the sons and daughters of God in two ways. In one sense, which helps us to answer and understand the first question of, 'Where did I come from?', we are all literal spirit children of our Heavenly Father, God the Father of Spirits. In the and/or our pre-existent life to this mortality, we were literally begotten spirit children of God the Father, Elohim, Jesus Christ there named Jehovah being the Firstborn Son of God the Father in the spirit. As the scriptures yeild, 'We are of the race of God, children of the most High (Ps. 82:6), the literal spirit offspring of God (Acts 17:29). We lived in the presence of God our Father, being in subjection to him according to the choice of our own agency (Hebrews 12:9). Yes, we each may say 'I am a son (or daughter) of God' (Moses 1:13). It is no wonder that the now Hymn, 'I Am a Child of God' hits a very real and tender emotion within us when heard and sung.
Listen to the hymn and/or if you wish, see the lyrics.
In the pre-existence, God the Father initiate the Eternal Plan of Eternal Progress whereby we might so fully maturate and become even as He Is. Because that entail that we must leave his presence and enter into a temporay mortal state, a Saving Redeemer was required that we might through him again return into the presence of God. Since God the Father of Spirits was already a Celestial immortal and eternal God, He would not retrogress back into a mortal state to so perform as our Savior and Redeemer. It required that one from among us who would and did so pertain unto this generation so take it upon himself to so perform as our Deliverer and Savior. Thus it fell to the eldest Son, the Firstborn in the spirit, even Jehovah to so take it upon himself to perform in behalf of we his younger brothers and sisters. So when the Father asked, 'Who shall I send?', Jehovah the Firstborn responded, 'Here Am I, send me." And thus was Jehovah so selected to be our Redeemer, Savior, Deliverer, Mediator, Advocate and Intercessor, to act as that redeeming agent of the Father in all things between the God of Heaven and the sons and daughters of mortality in all things.
Thus it was that in a second sense, we having entered mortallity according to our descent from Adam and Eve, we became a 'fallen creature' of the mortal flesh, subject to the failing of the nature temporal man. 'For as in Adam we all would so die, even in Jesus Christ would we all be made alive again. By that ordiance birth of baptism of water and spirit as explained by Jesus Christ to Nichodemus (John 3), we could become the gospel children of our Intercessor, our Ministering God, Jesus Christ, he who did performed the temporal creation according to the direction of the Father, he who was our Ministering God Jehovah acting in the stead of the Father in all things pertaining to this mortality, and he who it was that performed the atoning sacrifice for man in the garden and upon the cross, and who did mark the way of return to the presence of God by his example, the commandments he taught and that resurrection performed, that we might also be so resurrected and live again in the presence of God. And this in a large part does answer both that second and third question, of 'Why are we here?' and 'Where are we going?'
By our obedience and subjection unto the commandments and ordinance of God, we can have our natural man weaknesses removed and forgiven though the atonement of our Lord Jesus Christ or Jehoshua Messiah. He acting in behalf and in the stead of the Father relative to this mortality, could intercede on our behalf and through his adoption of us, return us again to the Kingdom of God, returning all glory to the Father. No greater love hath no man than this, that he was will to suffer and give his life for ours. And also God the Father so loved us of the world, that he gave forth his Firstborn of the spirit and Only Begotten son of the flesh as a willing sacrifice for the redemption of all men if they but bow down, and subject themselves unto him.
Certainly there is more to it and more to come to understand. But the basic design and plan of it is simple. Simple enough that a child might grasp it. And so ought we to receive it as a child, having a child's faith in it, being a spirit child of God and a welling redeemed child of our Lord and Savior Jesus Christ.