There are actually no references in the Bible that show the apostles believed Jesus was God, quite the opposite. You may have been lead to believe that but it's just false.

Looking for that blessed hope, and the glorious appearing of the great God and our Saviour Jesus Christ;

Perhaps you are overthinking that one.

You chose a good verse here: Colossians 1:15-16

If Jesus is the image of God then it directly negates him from being God. An image is a likeness or representation of a person or thing. An image is never the person or thing itself. Jesus is a representation of God. He is a likeness of God. Also, consider that worshiping an image of God is idolatry and therefore you are guilty of idolatry if you worship Jesus as God.

Yes people bowed before Jesus in reverence to him but never did they worship him as God. Jesus is the chosen Messiah and worthy to receive glory, honor, and praise. This is what the Bible plainly teaches.