Indeed Jigglypuff does have some identical animations to Kirby, in fact pretty much every unlockable fighter in the original Smash Bros. had some identical animations to one of the default characters, even Captain Falcon to Samus: https://www.vgfacts.com/game/supersmashbros/trivia-8690/

That however does not make them cloned fighters, especially based on how they're not treated differently from those that aren't, and cloned fighters as I said weren't even a thing till Melee as fighters that were easier for the developers to work on.

Jigglypuff was a clone of Kirby in 64 - his specials were different, but barely any other moves.

Luigi not being able to wall jump is a way of proving that he in the Smash Bros. series is not a cloned fighter of Mario, especially since cloned fighters weren't even a thing in the series till Melee, of which gave an actual cloned fighter to Mario in the form of Dr. Mario. Semi-Clones meanwhile weren't a thing in the series till Brawl, of which compared to Fully Cloned Fighters don't get treated differently in any way from the others. Then again what we saw be done with semi-cloned fighters in games that have them hasn't been done with Luigi either.