Did you know that there are still groups of people who have had NO contact with the outside world? Groups of people who have lived the same way for thousands of years? Primitives in the most literal sense. Sounds like the stuff of movies, but they exist
Think about this for a second. One species split up into two groups. One group is trying to figure out how to make sure their huts made of branches survive a heavy rain. The other group is building a 27 km circumference particle accelerator which will hurl protons at 99.9999% the speed of light. Both live in the same time period and both live on the same planet, literally right next to each other.
Same species and yet they are so different.