We already do all of this in drug discovery research before putting things into animals. We try computer modeling (very inaccurate but a good pre filter) then cell culture, and only after that do we use animals. Not only is it ethically the right thing, it’s the economical thing. Animal studies are crazy expensive (each mouse costs a couple dollars per day just to keep alive and you need a lot of them) compared to cell culture and modeling.

The problem is that in your scenario, many many more humans would be harmed. While animal models are flawed, there are no cell culture tools that even come close to recapitulating the system wide effects you get in a whole organism. Without animal tests, all the drugs that hurt a mouse (and there are very many that fail in mouse tests for this reason) would instead do it to humans.

You can ban animal research, but if you do, know that virtually none of the medicines you take would exist. It really is that stark.