What you described the trinity as being was Modalism, which the Nicene creed doesn’t teach. The definition of the trinity is in the Athanasian Creed.
To lay what the Bible clearly teaches:
There is one God. Jesus is God. Jesus always existed. The Holy Spirit is God. The Holy Spirit is referenced in both testaments. The Father is God. The Father always existed. Jesus prays to the Father. The Father and the Holy spirit are both present alongside each other at Jesus’ baptism. Jesus flat out equates the Father, Son and Holy Spirit together when talking of Baptism.
God is above creation and our laws. We only understand our unitarian nature - that we can only be in one place at one time. Just like how we being three dimensional creatures can only relate to three dimensions. So it wouldn’t make sense for God to abide by our laws, but to be manifest in three persons spanning time and space and the laws of this universe.