My Question then is this: Is it possible that Jesus might have been a good prophet (as many people believe) that was turned into a deity by his followers?
Absolutely.
It has happened many times in history and still is happening today. You have cults growing all the time with the leader being deified and glorified.
The cross has become a graven image too. People are praying to Jesus using a crucifix. That's the same idea of token you have in religions with images. The image, the statue, the stick, the rock, whatever, is not the spirit, it only represents the spirit, just like the cross only represents Jesus. Graven images... that should be a no-no.
Also, remember when Israel started to pray to the copper snake? God gave it to them. Is it a symbol of Jesus?
This question assumes that Jesus was at the very least a real person so answer accordingly.
I do think it's very possible that a leader for a cult existed. It's kind-a typical for religious groups to start that way. A leader to is elevated to prophet or divine.