You're making a huge leap there based on zero scientific evidence. No one has ever demonstrated maximum lifespan extension for mammals living in the wild. Experiments have been limited to animals living in nice safe, sterile cages. There's no free lunch in genetics and modifications that increase maximum lifespan are likely to result in other undesirable changes. Like suppression of immune response can be helpful but that comes with a huge obvious downside if you're ever exposed to random pathogens. Outside of some very limited genetic defects it's usually impossible to alter a single trait in isolation.
No one has ever done it is not in itself evidence it can’t be done, only that it is hard.
And my point was-no matter how hard human life extension is, mind uploading is many orders of magnitude harder. The first, it seems likely in principle that we could achieve it if only we knew the right genetic changes to make-now, you may be right that in a thousand years we still won’t work out in practice exactly what they are-but human life extension has a certain kind of theoretical in principle feasibility which could well coexist with practical infeasibility; mind uploading lacks even that level of theoretical in principle feasibility.
