I suppose it all comes down to terminology in a sense.
Rouquayrol and Denayrouze developed the first practical compressed air SCUBA unit; it being able to operate free from surface support air for short periods. These units worked and were sold to the French Navy.
Fleuss is considered the progenitor of the first practical oxygen rebreather SCUBA unit. Davis, Draeger, Lambertsen etc... all build off of his work. You could say Hass was at least equal to Cousteau in what they did but Cousteau was more the showman and there may have been some post war anti German sentiment at play as well so the world remembers Cousteau. Plus the oxygen RB became seen as unsafe for recreational diving unlike the compressed air Aqualung.
LePreiur really should be considered the first popularist of SCUBA because his units were used recreationally, as well as by Navy divers. LePreiur diving was quite popular in the 1930's and I would not doubt that Cousteau and the future URG nucleus were influenced by it. However, Ohgushi created much the same device before LePrieur but anti Japanese sentiment prevented it being well received.
Personally, I think Commeihnes and Cousteau/Gagnan are tied for the modern demand valve regulator. There isn't much doubt that the GC42 would have been widely available before the CG45 if Georges hadn't been killed in the war. Then what?
But who's the first is fickle, just like the topic of a thread. While Rouquayrol/Denayrouze devices were capable of SCUBA use, Navy divers shied away from it because the reserve tank was too small. Fleuss originally wasn't interested in SCUBA and was trying to make a fire and flooded mine escape device. LePrieur was inspired by Fernez, basically just adding a HP tank to his idea and Cousteau, Gagnan and the Commeihne's were all exposed to LePrieur and other developments of the 1930s. It's curious that LePrieur was military attaché and translator at the French Embassy in Ohgushi's Japan.
Oh, and that's an amazingly well preserved raft. If you didn't say different I would think it was a modern reproduction.