Jesus came for one reason. To save people from their sins. True, in order to be saved, you have to have at least a basic understanding of whom Christ is - but He could have told us all about Himself in the Word to a point. What happened when Jesus came, was he showed us the extent of His mercy and grace towards sinful humanity.
In His words, this is why He came:
Luke 19: 10For the Son of man is come to seek and to save that which was lost.
John 3:17For God sent not his Son into the world to condemn the world; but that the world through him might be saved.
3:18He that believeth on him is not condemned: but he that believeth not is condemned already, because he hath not believed in the name of the only begotten Son of God.
3:19And this is the condemnation, that light is come into the world, and men loved darkness rather than light, because their deeds were evil.
John 10:10
The thief cometh not, but for to steal, and to kill, and to destroy: I am come that they might have life, and that they might have it more abundantly.
That is one reason. He came to teach who He was and what He was about. Saving folks from their sin is part of what He is about. It's important for folks to know Him, what His promise is, and what one must do in order to be saved. His teachings included about Him and His Spirit, so that others could know the reference for judgment.