Revelation 1:17-18 (KJV) First and last

Revelation 1:17-18 (KJV) And when I saw him, I fell at his feet as dead. And he laid his right hand upon me, saying unto me, "Fear not; I am the first and the last:
I am he that liveth, and was dead; and, behold, I am alive for evermore, Amen; and have the keys of hell and of death."

The speaker above is most certainly Jesus, as he was dead. It can't be God because he is inherently immortal and cannot die.

In Isaiah 44:6, that is God the Father speaking, who's name is Yahweh.

Yahweh is always just God the Father. He's the only true God.

The trinitarian claim is that both the Lord Jesus and God almighty Yahweh share titles.... therefore Jesus is Yahweh.

Alpha and omega.
Beginning and end.
First and last.

There is an explanation for these shared titles without violating the unitary monotheistic faith of Jesus and the apostles.

God the Father is the beginning and end of physical creation. He spoke the earth into existence and stretched forth the heavens alone. The title first and last connected with the flavour of physical creation can be garnered from verses such as...

Isaiah 48:12-13
Isaiah 41:4
Also in Isaiah 44:6 he has the same title first and last, and later in verse 24 he emphasises his sole role in creation again.

Jesus is the first and last, alpha and omega of the NEW creation. He's the firstborn of all creation, the beginning, firstborn out of the dead (Col 1:18)

Rev 3:14 says he's the beginning of the creation of God.... that's the new creation in Christ.

Jesus is also the end, because he has been ordained by God to judge the world on the last day, after which he will hand back the kingdom to the Father.

Acts 17:31 (KJV) Because he [GOD] hath appointed a day, in the which he will judge the world in righteousness by that man whom he hath ordained; whereof he hath given assurance unto all men, in that he hath raised him from the dead.

There seems to be some difficulty in the trinitarian claim.

If you are going to say that the shared titles means Jesus is the speaker in Isa 44:6, then who is that speaker in Isaiah exactly. Who is that Yahweh? If its the triune God then Jesus is not the triune God in the doctrine.

If its God the Father speaking in Isaiah, then Jesus is not the Father in the doctrine of the Trinity. So that makes no sense either.

And I don't think any trinitarian would say its just Jesus talking in Isaiah, as that speaker keeps talking about creating everything on his own, but the doctrine claims that God the Father created everything, through Jesus at the beginning. So that violates trinity doctrine too.

And if Jesus in Rev 1:17-18 is the same as the person (or thing?) speaking in Isaiah.... then can that speaker in Isaiah ever be dead as is stated in the Rev verse?

Who is that speaker in Isaiah 44:6 exactly? It seems the contradictions are insurmountable within trinity doctrine