Am I the only one who plays TTRPGS wihtout levels?
There are plenty of games without levels. The ones off the top of my head that I've played and/or ran included GURPS, Torg, Call of Cthulhu, Over the Edge, Unknown Armies, and Mutants and Masterminds (though there are levels, but they do not have inherent bonuses in them like D&D).
Actually, Call of Cthulhu has one of the more interesting experience systems. No XP. Did you use that skill? Roll percent dice. If you get
over that skill, then you learned something and can increase it. Albeit, that system wouldn't hold the attention of the average gamer, but nobody expects CoC characters to survive for long anyway.