UFC I, yes, it was a display for Gracie Jiu Jitsu.
UFC II however, added exactly what you were looking for--Remco Pardoel (European Judo Champion), Orlando Wiet (while not super elite in Muay Thai, he did hold a Muay Thai title) and Minoki Ichihara (a well respected Karate champion.)
And Royce Gracie still won.
You have to judge fighters calibre by looking at their peers.
Remco Pardoel while a great judoka, all props to him - he was not of the same calibre as Royce Gracie, let's be honest. He was a national Junior Judo champion of the Netherlands.
Orlando Wiet while a great fighter, props to him again - he was not an elite Muay Thai fighter or of similar calibre to Royce Gracie, nor did he hold any respected Muay Thai title - you have to judge him by the quality of his peers.
Minoki Ichihara was a daido juku kudo national champion. Daido Juku in the 90's was extremely small & was a very small organisation. He wasn't a well respected karate champion - unless you consider fighting in a relatively small unknown karate organisation (at the time) - well respected - daido juku wasn't what it is now back in the 90's. I mean I think it prudent to point out that he only fought once professionally and that was against Royce Gracie - which he lost. I mean in comparison to his peers he wasn't a great karate champion many of whom were professional fighters.
I think a lot of people overlook or simply don't want to acknowledge that the early UFC's were a showcase for GJJ and later mixed martial arts. I think a lot of it comes down to the unfamiliarity of martial arts outside of their own especially back in the 90's.
Minoki Ichihara was a relatively unknown national kudo champ in the Karate world and his first fight professionally was the one he lost against Royce, Orlando Wiet was not a great Muay Thai fighter - if the early UFC's had a guy like Kiatsongrit or Sakmongkol than I'd happily agree with you and Remco Pardoel was only a junior national champion of Judo who'd never had a fight.
100% the early UFC's were historic landmarks in the history of martial arts and changed things but let's see them for what they were a showcase of GJJ that later developed into a showcase of different styles. They were not a showcase of the best martial art or the best fighter on the planet because the vast majority of best fighters on the planet at the time did not compete in any of the early UFC's and more importantly most martial arts were under represented, not represented at all or simply didn't have the same calibre of individual competing that other styles had. While Royce definitely wasn't the greastest GJJ practitioner at the time - he was elite - anyone who knows about Daido Juku, 90's kickboxing/Judo cannot say the same for all the guys you mentioned. I mean it's laughable to suggest they were elite the same way Royce was.