If you are one consciousness living all lives then your question about taking someones place dissolves. There is no other person whose life you stole. There is only you wearing a different mask. Time from the human perspective is linear but from the perspective of whatever runs this whole thing there is no reason lives could not be run in sequence in parallel or outside of our concept of time entirely.

Philosophers have played with this. Versions of Hinduism Buddhism Advaita Vedanta and some modern thinkers like Schopenhauer and Metzinger all flirt with the idea that there is just awareness appearing as many. Simulation arguments and Many Worlds talk in similar shapes with different vocabulary.

The important part is not whether you can prove it but what happens if you live as if it were true. You did that experiment for a day and noticed that irritation dropped off a cliff. That is not trivial. That is a data point. You changed your ontology and your nervous system responded.

On the ethics

If everyone is you then enemy becomes a category error. You are basically punching your own mirror. Even if you decide the metaphysics is poetry not physics the behavior it produces is hard to argue against. You can decide other people are separate and still choose to treat them as if they are not because that stance leads to fewer regrets and less internal noise

https://m.stacker.news/134618