I don't think 5e is an especially coherent game.

I can't speak to how well 5e would work with dark sun, but 5e is very much about epic heroism. Levels 1-3 exist entirely as an introductory system to avoid overwhelming new players - IIRC, there are official suggestions to just skip them if playing with experienced players. Additionally, they are designed to go incredibly fast. The meat of the game really starts after that, and the characters quickly catapult to functional super heroes.