Again Jesus spoke to them, saying, “I am the light of the world...” -- John 8:12 (ESV)

but...

This is the message we have heard from him and proclaim to you, that God is light, and in him is no darkness at all. -- 1 John 1:5 (ESV)

which was also written in the Old Testament:

The LORD is my light and my salvation... -- Psalm 27:1 (ESV)

Therefore, some conclude that Jesus is the LORD God. However, they ignore Jesus own words when he said:

Jesus answered, “It was not that this man sinned, or his parents, but that the works of God might be displayed in him. We must work the works of him who sent me while it is day; night is coming, when no one can work. As long as I am in the world, I am the light of the world." -- John 9:5 (ESV)

Jesus does not use "light" as his identity. He said "as long as I am in the world", which means it was a temporary role that Jesus fulfilled.

Everyone is supposed to be lamps or light for God:

For it is You Who light my lamp; the LORD my God lightens my darkness. -- Psalm 18:28 (ESV)

For so the Lord has commanded us, saying,

“ ‘I have made you a light for the Gentiles, that you may bring salvation to the ends of the earth.’ ”

And when the Gentiles heard this, they began rejoicing and glorifying the word of the Lord, and as many as were appointed to eternal life believed. And the word of the Lord was spreading throughout the whole region.

-- Acts 13:47-49 (ESV)

God can "shine" His light by any human "lamp" that serve Him in righteousness. For example John the Baptist was also "the light of God":

If I (Jesus) alone bear witness about myself, my testimony is not true. There is another who bears witness about me, and I know that the testimony that he bears about me is true. You sent to John, and he has borne witness to the truth. Not that the testimony that I receive is from man, but I say these things so that you may be saved. He (John) was a burning and shining lamp, and you were willing to rejoice for a while in his light. But the testimony that I have is greater than that of John. -- John 5:31-36 (ESV)