The level of automation necessary for manufacturing in space is going to be very close to removing humans from the process entirely. Taking it that one step further and having robots manufacture robots would eliminate all the issues with keeping flesh-and-blood human bodies alive.
Honestly I sometimes think the best legacy humans can hope for is giving birth to AGI. Machines would be much better suited to forming a solar or galactic civilization than biological entities ever would be. If we're lucky, humans or meta-humans would still be around as what essentially amounts to pets.