Never seen the helmet in this much quantity in the same place and each of different design.

Yes it the artist, who come up with different ideas in his mind, and the best thing is he doesn't stop, he worked to make his ideas real.
Art comes from the heart and deep thoughts.
I already said in your comment section that art does not require any explanation from the artist, it speaks itself, and we can see this clearly by these helmets. No one will ask anyone who is the maker of these helmets, they just look around and select the one they chose to be perfect for them.