space colonization is the only one that is so simple that even contemporary humans have a definite recipe for doing it that would probably work

Maybe. The nearest solar system - which would apparently take about a hundred years to reach - is over four light years away, and it isn't even certain whether it has any planets. The closest planet that is actually known is apparently ten light years away, which would then take 250 years to reach. It's obviously not impossible that we - or some future superintelligence - might manage to build a craft that survived that whole journey intact enough to continue with a colonization effort, but it doesn't seem obviously possible either.