You say the homeless problem "can be solved the next day should we decide to"; but we haven't decided to. So either this isn't a simple political problem and there are practical concerns we haven't figured out yet, or there's a worrying gap between what is possible to do and what we're willing to do. And if there is no mechanism to close that gap, then you just can't solve aging universally. At best you can only solve it for a very small select few, at which point you might be doing more utilitarian good by just helping the homeless right now.
The current lack of universal housing, universal health care, suggests very strongly to me that curing aging is not in fact an effort that "affects everyone universally"; because I don't believe that universal distribution of a cure is simple or a straightforward question of political will, and I wonder if it actually does have massive social/political/practical complications behind it that are going to be very difficult to solve, and I wonder if (under a strict utilitarian perspective) solving that problem of universal access to basic resources is not the more important priority.
If we're all just working on our own stuff in parallel, fine. I actually think the utilitarian way of looking at this is kind of nonsense, and I would encourage people not to use this lens. We should not be ranking social problems in this way, it's fine for some people to focus on technical problems and its fine for some people to work on social problems. But if we are going to use this lens and we are going to rank problems, it seems like fully solving the aging problem is almost strictly dependent on solving the political problems first.