Because there is no level-system. Sophistication is measured by ages.

Yep

what do you mean

As example: first "level" is bronze age. But if you are asking this because of points; you don't need to "reach level 5", just play for a while and you'll get the points.

When you play the game go to the Tech Screen on the left looks like a lab glass then you will see all the techs use your forge points which you get 10 daily i belive or (every few hours) gather the needed items for each one and you will age up. Atm im Early Middle Ege half way through