Of course... "...the Scriptures looked forward to this time when God would save the Gentiles also, through their Faith. God told Abraham about this long ago when He said, 'I will bless those IN EVERY NATION who trust in Me as you do.' And so it is: all who trust in Christ share the same blessing Abraham received." (Gal.3:8 LVB Living Bible)
"...I will bless those who bless you and curse those who curse you; and the ENTIRE WORLD WILL BE BLESSED BECAUSE OF YOU.'" (Gen.12:3 LVB)
"...your Offspring [Christ] will be a blessing TO ALL THE NATIONS OF THE EARTH -- all because you obeyed Me..." (Gen.22:18 LVB).
The Salvation of the world [through Faith] and the coming Kingdom of God is the running thread of God's Promise [and the Gospel; Good News of God] throughout The Bible, that began with Abraham.
"You can see from this that the real children of Abraham are ALL THE MEN OF FAITH who truly Trust in God." (Gal.3:7 LVB)
"And now that we are Christ's we are the True descendants of Abraham, and all of God's Promises to him belong to us." (verse 29)
God has His times and seasons. Actually there were a few Gentiles that received salvation in the Old Testament. Rahab in the Book of Joshua was one and Ruth in the Book of Ruth was another. There were more, but this was the exception to the rule. During Jesus' time on earth more Gentiles are mentioned and then finally when the Jewish people rejected Jesus as the Messiah it was time for the Gentile to be accepted by God on a different basis, although Salvation has always come by faith in God, God created a time when mostly Gentiles could come to Him freely and in great numbers. Salvation to the Gentiles was mentioned in the Old Testament a number of times, but the timing was God's.
Yes, James is not mentioned in the Old Testament.
The colt, donkey ass were mentioned in the old testament.
No, John the Baptist is not mentioned in the Old Testament. He is a figure in the New Testament of the Bible.
Yes, Jonah is mentioned in the Old Testament in the Book of Jonah.
The judges mentioned in the Bible are from the Old Testament.
Abraham is first mentioned in the Old Testament.
Titus is mentioned in the New Testament.
Most likely God is mentioned in the Old Testament in what he said and did for His people.
Yes, baptism is not explicitly mentioned in the Old Testament scriptures.
The name is mentioned 26 times in the Old Testament.
The word "Heaven" is mentioned 266 times in the Old Testament.