

Non-religious but likes plot analysis.
An important factor here is free will. Without free will, one may easily have a perfect utopia of the kind you think an omnipotent God should be able to achieve. But it would be a meaningless utopia; like a kid playing with toy figurines, just deciding everything we say and do.
God doesn’t want that, and thus self-impose a limit on the omnipotence to not interfere with our free will. We are children that need to be taught, rather than marionetted to “save us” from the negative urges of free will.
Here, the (self-)sacrifice of Jesus enters. It is not about God using Jesus to fulfill some perverse quota of pain and suffering that God has decided is due before we are allowed into heaven. It is more about what humanity must experience for the lesson that makes heaven remotely possible as a concept. Only through pain and suffering will we come to understand how our actions affect the world and those around us. Jesus takes (some of) the pain and suffering “in our place” with the aim that the message will resonate with people throughout the ages to teach us about love and understanding, making the concept of a heaven possible despite our nature as (non-brainwashed) beings of free will.
In reality, even after 2000+ years, we still seem pretty far off the mark. Maybe the lesson didn’t take the way it was intended; free will is a fickle thing. Or maybe God is playing an even longer game.











Time travel as a sudden jump seems one of the least plausible implementations, since we have no idea how to do such jumps even in just space or forward in time; and allowing for it would break a lot of physics.
More plausible alternatives include a space-time bridge, meaning both sides can follow Earth’s reference frame; or the Primer-type where one can reverse time in an isolated box in a way where you can only travel backwards along the Box’ trajectory and you have to wait inside that box for some time while you move backwards in time along that trajectory.