This is pretty basic freshman year philosophy stuff. If you're finding it really crazy and eye-opening then this is probably an area where you could blow your mind a lot!

It's long, but it's reasonably well-organized and I think it makes straightforward sense. I didn't make up the terminology.

None of this depends on free will or karma - at least not in the sense that it requires there to be an external punisher who enforces compliance with moral rules or a externally verifiable sense that things could have happened in ways other than they did. A lot of ethics does involve seriously thinking about why anyone would want to be ethical, and it doesn't start and stop with just the supernatural or speculative.

Something can be "the right thing to do" because, for example, it leads to you becoming the person you want to be. And whether you have free will or not does not matter. It can be the right thing to do because it's what you would want people to do for you, which also isn't an exotic concern.

In general this sub is way too obsessed with speculative questions of free will, sentience, determinism, consciousness, and "nihilism" and not really concerned with or interested enough in what life is actually like and how philosophy as a broad literature might give you a systematic way of speaking about it and making some sense of it. Of course you could accuse philosophers of the same thing but that's not always the case.

I just think your initial question in this comment thread isn't really a "free will" question - because whether you have free will or not I think if you're talking about change over time there is a role for random chance as a retroactive explanation that has a role in grasping moral situations.