There are several theistic religions - which have a personal and creator God - but what difference does Jesus make? If God is The Creator - then why should we need to bother with Jesus?
Answer: Jesus is what enables us to share divinity.
That is what Jesus adds to theism. Without Jesus, the gulf between God and Man is infinite and unbridgeable.
But Jesus is Man and God, and he joins the God-Man gap - showing it is not infinite.
With Jesus Man can also be God.
Furthermore (and most important to each of us), Jesus bridges the gap between our-individual-selves and God; making it possible for you and me and everyone to share divinity.
Because Jesus offers us resurrection to life eternal - which just-is divinity. We shall, if we follow Jesus, become immortal, indestructible, participators in creation - while remaining our-selves!
With Jesus - you can/ I can become a god, as was Jesus. Jesus is 'about' our sharing of divinity - Jesus removes that measureless gulf betwixt God and Man which is left-open-forever by theism-without-Jesus.
So Jesus is important if 1. We personally wish to share in divinity; and 2. if we believe that this goal is indeed possible for us to attain personally, by the means Jesus taught.
If we don't want to become divine - or if we don't believe it is possible (or if we believe it is incoherent nonsense to want to become divine) - then there is indeed neither valid point nor purpose in Jesus.
Note: Like CS Lewis - when converting to Christianity from atheism (in my case being an atheist from about age 6 to 49) I went through the phase of theism (believing in a personal God-creator, but in a non-denominational way) before I became Christian. Understanding the need of Jesus Christ was not something that came naturally or easily to me. And indeed I continue to find most of the explanations for why Jesus is necessary (and therefore why God the creator is insufficient) to be incoherent; inconsistent with the Fourth Gospel (the heart of scripture), and/or inconsistent with core Christian values - such as God being our loving Father and we his children. This is why I continue to seek ways of expressing the necessity of Jesus in ways that are both coherent and simple enough to be of practical value.