Your premise reminds me a lot of mushoku tensei.
My main criticism for you is that you need to work on your subtlety with your writing. You know, "Show, don't tell". You want to be able to give readers bits and pieces of information without directly saying it. This is much harder to balance in book form like you have, but it's still a valuable skill.
My 2nd recommendation is; add an interesting twist to your isekai story. They're really common on tapas right now so you'll need to really work at it do differentiate yourself from your competition. The story needs a bit more of a unique twist to it.
Just off the top of my head, I'd say that you should have something crazy happen relatively early in the story, and the best way to do that is by having a plot-twist associated with the person that Connor ends up replacing. Like, what if connor has to learn to share a body with the original "Thomas" as the baby's mental capacity increases while they grow up. It'd actually be pretty funny if they could each only control half of their shared body. Just a thought.
