It's very fortunate that rockets are not the only way to get stuff into space, and more importantly, that we don't need to literally bring a whole factory and the input materials up on a rocket but instead use resources available in space.
Even if we actually had to bring everything from Earth, Starship is cheap and powerful enough to build an orbital ring which would make orbital lift nearly too cheap to meter.
Assuming you're hitting on carbon stuff. There are simple solutions even with rockets. For instance liquid H2 / liquid O2 rocket engines are a thing - this is what the Space Shuttle Main Engine used. [1] Reacting hydrogen with oxygen is, counter-intuitively, an extremely effective propellant! And the exhaust is literally water vapor.
Some reason SpaceX decided on methane based propulsion are because it's more safe/stable than liquid hydrogen, because Mars is the goal, and the Sabatier reaction! [2] You can create methane + water from reacting CO2 + hydrogen. And Mars has practically infinite CO2 + hydrogen, which translates to practically infinite fuel + water. Add in fully reusable rockets and you have one heck of a nice starting framework for colonization, that in some ways almost feels too convenient.
It's even worse than that. A space elevator, the only thing that could conceivably replace rockets, requires materials so strong that they don't exist in our universe.
Space is like the internet. You can communicate through it, but sending matter is nigh impossible.
Not true - an orbital ring doesn't require any scifi materials, though the engineering is not yet there. And you can build magnetic accelerators, that's fully possible with current knowledge of science and engineering.
Even if we actually had to bring everything from Earth, Starship is cheap and powerful enough to build an orbital ring which would make orbital lift nearly too cheap to meter.