My understanding is that all these are Pagan-Christian wishful thinkings, none of them make one G-d. One who couldn't' save himself from a cursed death on Cross, how could the save the mankind?
They are stories adapted to carry a message of peace and hope completely different from the pagan stories. One NT writer says plainly Jesus prays to God to be delivered from death. The gospel of John explains best that the Logos of God dwells in many, Jesus being the first. Its similar to saying we can share as a group God's traits.
The trinity is a restatement of these things having derived them separately through a Greek philosophical path. You have the Father (that from which we inherit our traits), then you have the Son (that which we have received from the Father), then the Holy Spirit (scripture, wisdom etc).
Why the trinity? There are pagan trinities, but this is different. When Christians speak of the Father it ought to be a kind of admission that we have not yet gotten to the inheritance. Its hard to pick up on this perhaps, and a lot of Christians acts as if we'd already arrived. Jesus would say Christians are storing up treasure in heaven, perhaps alluding to this scripture:
"You heavens above, rain down my righteousness; let the clouds shower it down. Let the earth open wide, let salvation spring up, let righteousness flourish with it; I, the LORD, have created it." (Isaiah 45:8)
So things in the NT writers are not always as clear as people would claim. Often they are futuristic or mystical. If you look at any building its the same way. First come the plans, then come the long years of construction during which no one lives in the building, but when its done it looks as if its always been there.