Im confused by what you mean by most heartless weren't wearing the emblems. Most almost all but a very few pure heartless were wearing the symbol thats xehanort created, as for the nobody's emblem it is possible that xehanort created the emblem but you never find a nobody development plant like you do the heartless. My guess is that the symbol is inhearant to all nobodys whos hearts werent strong enough for them to retain their human form. The nobody emblem would then be created by a higher being that existed before xehanort because just like heartless, nobodys had to have existed well before xehanort was even born
As for the new creatures it could be the same as the nobodys in the respect that Xehanort had nothing to do with it, or either he did. Even though that statement is a big DUHHHHHHH statement pointing it out is the purpose of explaining it. Mearly that xehanort may NOT have had anything to do with it.
Lol, I guess where im leading to is some sort of "Intelligent Design" in the universe of Kingdom Hearts
Kami Nomura Ka?