I think you have to prioritise the problems though.
Atm putting research into expanding lifespan will just exacerbate our problems with resources and population.
In the west in the last 70 years we've made massive strides in increasing liveable lifespan which is why my mum at 80 is still golfing, gardening and driving. Thats great but western nations are struggling to deal with ageing populations, with the social problems caused by immigration required to get people of working age, and the rest of the world is struggling to deal with our consumption of resources.
Until we deal with how to provide resources for our society without destroying our planet, work out an acceptable work/life balance when we are living much longer active lives, and work out how we're going to manage with a 3rd world thats not just going to accept our privileged status it should be an either/or situation.
I've prioritized. I'm factoring in my explicit concerns with people's implicit behaviour. I'm not your opponent. People who live their lives unconcerned with the issues you raise (explicitly and implicitly) are your opponent. You're trying to convince me to let my parents die earlier than they need to, and that's a conversation you cannot win. Not because I am stubborn, but because you'll not even convince yourself.
Okay, so at the personal level, you seem to be fine with your mom being still alive. You've not pushed her onto an ice floe, even though her footprint is going to be ten to 100 times that of any starving kid. She's contributing to the problems that you list merely by being alive. Implicitly, you're not okay with her dying earlier in order to provide this resource break that you claim is required. But you'll mention your concerns to someone who thinks that death is an enemy.
That creates some weird coincidence, where her current lifespan is optimal? That doesn't make any sense. It's either too long or too short. And we cannot square the circle, because you devote time and resources to your mom's well-being, even at the cost of these problems you describe. Your implicit behaviour doesn't match your explicit statements. As soon as you spend a single cent or a single second on her health, your position becomes hypocritical. It makes more sense to build a position that isn't hypocritical, but is also moral. Instead of letting your mom die so you can reduce her footprint, create solutions.
After that, it's a function of where to put your next resources. If you're looking to improve things at the bottom, I'm all on your side. But you also seem to think that 100,000 deaths per day are buying you time when it comes to solving the problems that you want solved.
My position is that being in favor of this suffering and death is both a failure of imagination and a lack of devotion to solving the problems you want solved. Environmentalists cannot even convince each other to eat less meat, even if they can convince themselves. But you'll not find many who can convince themselves to let their parents die earlier than they need to.
Please consider, I'm cognizant of the problems you describe. I'm reasonably active on a fair number of them, even. I just don't include mass deaths as acceptable in my solution set.