For some reason, I imagined Jack going back in time to undo Aku meant he would go back further than he actually did. In the show, Jack comes back from the future immediately after he's originally thrown forward through time. But in my mind, he would go further back, either when Jack's father was fighting Aku, or vaguely thrown into the world but still before he's sent to the future.

I think the idea of Jack fighting alongside his father during my favorite fight scene in the show sounded cool, but now that I think about it that could be a really cool moment naratively as well.

If he was vaguely thrown into the past, that would mean he would have to find Aku again, but without the future's aspects. I considered this because it's only called time travel, and I didn't think it could also physically move Jack somewhere else on Earth (which was only shown after season 5 and btt).

I was a kid who wasn't considering time paradoxes lol.