The first Portal did try to have some """"lelsorandumb"""" humor, but honestly, even the Monty Python are lelsorandumb Reddit memespouters according to neo/v/. Any attempt at comedy that didn't appear in the latest "hah, how spontaneous" slice of life Chinese cartoon is lelsorandumb so you might as well ignore that criticism. Portal was never serious. It wasn't as stupid as TF2, but it definitely was fairly stupid.
The problem with Portal 2 is not that the puzzles themselves were easier. Many of them were in fact more complex, they just didn't rely on reflexes and motor skills as much as the first one since they fixed some quirks with the original game. For example, light bridges would be a shit feature using the first Portal's mechanics because with enough reflexes you can use them to escalate (just try any HAMMER user-made level, as they don't have the snap to grid thing Portal 2 levels have). I also remember a challenge level in the original Portal that was almost impossible because you were supposed to build up momentum but the game kept resetting the orientation of your camera to some arbitrary fixed point every time you entered the Portal, so you pretty much had to make a 2fast2furious 360 n0scop3 to aim the place you wanted to shoot at.
Portal 2 was easier because it wasn't as quickly dispatched as Portal was. The puzzles were actually better, it just was an actual puzzle game instead of a puzzle-action game
