Ok... so here's what I think it means...
I think there was this innocent boy (Symbolized by him hiding from the scary thing) riding the train and this creepy guy came in and kidnapped him and took him back to his house and molested him (Symbolized by the bird thing lifting his robes for the snake thing to come and and bite the kid) . He ran away and some authority figure protected him (Scuba man) when the molester took chase. The kid took a peice of the molester with him, though, because the trama was too great. (Symbolized by him taking the eyeball)
Am I in the ballpark?