What have we done so far in space travel?

That's a rather general question which could take entire books to fully answer. Perhaps you could be a little more specific or at least do a modicum of your own research on this VAST subject?

Nearly 50 years of research into the effects of micro-gravity on the human body and very little else.
Flying around in circles..excuse me, ellipses.

We've learned a lot about how humans live in zero gravity.
We've learned a lot about our Moon--we sent 12 people there.
And, we've also learned a lot about the other planets in the solar system, (as well as the Sun), with our robotic probes.
Knowledge about our Sun, for instance, also gives us insight into how the Earth's weather behaves.
Also learning about the other planets also gives us a unique perspective of our own planet, as well!
For example, without our knowledge of Venus' runaway greenhouse effect, the theory of global warming on the Earth would have never taken hold.
And, perhaps, we may be on the verge of discovering life on other worlds, (perhaps on Mars, Europa, Enceladus, or Titan)--the possibilities are endless!