Suppose one could send a futuristic molecular assembly to another star system that can use resources of the planet to build anything from a bunch of bits.
Then to send that equipment requires sub light speed - say 0.1C
Once the equipment is on the other planet, then sending information is 1C.
I think the assumption that we need to send humans to other planets is not true.
Once we figure out how to build better space faring beings that we can stream our consciousness at light speed, that seems more feasible for space travel.
Humans are squishy meat bags that need to eat multiple times a day, pee, poop, sleep, stable temperature and many other needs to survive.
There’s a reason why humans have only made it to moon which is about 400,000km but for all other planets only rovers have touched down.
I highly doubt Elon/SpaceX will have living humans on Mars in our lifetime, it’s much more likely they’ll have their Optimus robot or a descendant of it on mars receiving instructions from Earth.
Human intelligence and consciousness isn’t that special. Just an algorithm running on biological hardware.