In the first Rayman, there's absolutely nothing unique nor peculiar about Rayman's appearance and nature: he's not the only creature having Floating Limbs, he's not the only one with an unusually large nose. Floating Limbs are universal in the first game. And regarding the large nose, it's also shown by the Magician, Tarayzan and the Musician (together with his family). They are nicknamed, in fact, "Rayman's species" in the fandom. Not only those characters, but also others that don't have the large nose (like Betilla or Space Mama), if compared to most creatures encountered in the game, are the only one that fit the Ambiguously Human trope.
Furthermore, Rayman doesn't magically appear at the beginning of the game: he's literally a bystander, first shown napping on a hammock, who Jumped at the Call. The idea of him being a sorta weird and unexplained manifestation really was introduced in Rayman 2.
Finally, his powers. Rayman has zero powers at the beginning of the first game, contrasting with him already having them in the following installments. Now, a normal human being doesn't possess Helicopter Hair, not is capable of throwing absurdly strong and long ranged fists. Hanging onto ledges or running fast may seem bland as acquired abilities... but in reality, not even those are things that most people are truly capable of doing. Especially hanging onto ledges, is difficult.
So, it seems plausible that the original idea for the Valley's inhabitants was to be Human All Along, and Rayman's specifically to be an Empowered Badass Normal.
