Jesus called God his Father , but if we look closer we see that Many Prophets called God their Father , and no Prophet including Jesus called themselves the only begotten son of God , except for David (Psalm 2;7) KJV , now let's see the Prophets who called God their Father identically to Jesus :
".....What shall I do when my heavenly Father hath so commanded me ? (Sifra to Lev; Qedoshim 20,26)
"....Since I have done the will of Abba who is in the Heavens "(Lev R para 32)
"......These buffetings have made me Love my heavenly father" (Midr.Tehillim 12:5)"
"I will exalt the lord saying 'thou art my father" (ibid 51:10)
"Beloved are Israel for they are called Son of the Highest" (Aboth 3:3)
**lets now see what the Jews wrote in their Apocryphal books .
"But thy providence O Father Governeth it" (Wis. 14:3)
"O Lord, Father and governor of all my life.."(Eccl 23:1)
"O Lord , Father and G-d of my life.."(Eccl 23:4)
The term "Our Father which art in Heaven" is one of the three major forms of the address in Jewish liturgy .
(The following verse is God talking to David about Solomon)" I will be His Father and he will be my son. I will never take my love away from him, as I took it away from your predecessor. (Chronicles 17:13)
Yet the Israelites will be like the sand on the seashore, which can not be measured or counted. In the place where it is said to them, 'You are not my people,' they will be called 'sons of the living G-d. (Hosea 1:10)
The kings of Israel are referred to as sons of God because they are to be His representatives, ruling in his place on earth over His people.
"I said, You are Elokim; you are all sons of the Most High" (Psalm 82:6 )
In conclusion, we see that Jesus only said a phrase that was commonly said by Jews in his days, and Jesus did not claim to have a monopoly on son-ship with God. We are all God's children, Jesus is not the only one and never claimed to be the Begotten one.