Isolation

Isolation will always be part of the human equation

Any human colonization will always suffer from long communication times due to the speed of light, there is currently no real life science fact such as Sci-Fi Sub space and other ways to overcome speed of light communications.

Even nearby possible target systems able to harbour the large populations required for the critical mass of people required to build all the infrastructure to make the next leap into interstellar space.

The distance between large populations in other solar systems will most likely to be in the 20-30LY range in the habitable Galactic Ring of the Milky Way, this will mean two way communications between colonised systems to be around 60 years.

Human Travel between systems will be very limited, even the fastest transit times for humans will be slow due to the accelerations the human body can sustain over time, if possible a 30LY trip will take 30 years to accelerate to near the speed of light and another 30 years of deceleration. Even with humans placed in some form of cryostasies there are acceleration limits, if the human passengers are to be confined then the need for some sort of artificial intelligence either built into the ship or of an AI robot with auto repair systems built in.

The likelihood of a newly colonised system to a further system may well take 1000 years

As millennia of time goes past the different human civilisations created will start to diverge and grow distinctively different from those on Earth, with only a level of technological information transferred between them.

one other option may be for AI robots to explore and then teraform any suitable systems before Humans arrive this may lead to a Sci-Fi scenario of a new robotic species.