Jesus knew 0 of God being a trinity.The original Nicene Creed was first adopted at the First Council of Nicaea in 325. In 381, it was amended at the First Council of Constantinople to its present form. This amended form is also referred to as the Nicene Creed. In both cases, the Father, the Son, and the Holy Spirit are God either explicitly mentioned or by virtue of the fact that they're worshiped as God.
This is not 3 Gods because the word God refers to the divine nature which is one, just like human nature is 1. We all have the same one human nature.