Prospects/Journeyman are young or inexperienced fighters who show potential to be future breakthrough stars. Prospects are a step above novice fighters and a step below contenders and gatekeepers. Only one of the fighters you listed is actually a prospect. It would be like calling Cain, Pettis, Aldo, Nog, and Dan Henderson prospects.
Aoki is an 11 year veteran with a record of 37-6-1 (44 fights under his belt). He is current ONE FC champion and former DREAM champion. He has 2 more fights than aged veteran Hendo. Aoki falls in the legend/champion/veteran category (farthest from prospect a fighter can get without being a retired hall of famer).
Askren is undefeated and current ONE FC champ and former Bellator champ. He falls in the champion category and he is one of the best WWs in the world.
Tybura is M-1 champ and just tore through some top HWs outside UFC over the past two years. He's a champion, not a prospect or a contender. Same with Moraes.
Bibi was a champ in DREAM and now a champ in ONE FC. He is also a 10 year veteran. He falls in the champion/veteran category and he is one of the best BWs in the world.
Ishii is former IGF champ and is a top 15 fighter outside UFC. He's a 5 year veteran with 17 fights. He falls in the contender category (not prospect).
Really, Spong is the only MMA prospect you have listed. Spong fits the prospect definition because he is 2-0 in MMA and shows a lot of potential based on his kickboxing background. He only has 2 years in the sport as well which also fits the definition. He is inexperienced in MMA, he is undefeated at 2-0, and he shows promise to be a future breakthrough star, making him a prospect. I wouldn't classify Spong as a novice based on his excellent kickboxing and Muay Thai background.