Is he the only one mentioned in the bible as the son of God ?!!

There are more than 18 biblical verses stating that there are sons of God beside Jesus

These are few examples

Exodus 4:22 Then say to Pharaoh, ‘This is what the LORD says: 

Israel is my firstborn son.

-Psalms 89:26-27 

“I have chosen David as my first-born son, and he will be the ruler of all kings on earth.

-Deuteronomy 32:19

 The LORD saw this and rejected them because he was angered by his sons and daughters.

-2 Samuel 7:14 

I will be his Father, and he shall be My son.If he commits iniquity, I will chasten him with the rod of men and with the blows of the sons of men.

-Isaiah 43:6

 I will say to the north, ‘Give them up!’ and to the south, ‘Do not hold them back. Bring my sons from afar and my daughters from the ends of the earth.

Ephraim is my firstborn son.

Jeremiah 31:9 They will come with weeping;they will pray as I bring them back.I will lead them beside streams of water on a level path where they will not stumble, because I am Israel’s father, and Ephraim is my firstborn son.