The package was originally printed with a pair of wings and "the world in time". In fact, the contents of the package and the specific things inside are not clear, because this package only represents the hope of a protagonist on a desert island, because he hopes to have the opportunity to go back and deliver this package. From the beginning of the story, he showed a professional attitude and understood that he was very responsible for his work. So the packaging is more symbolic and movie clues, and the content is not that important.
Another thing worth mentioning is the pattern on the package-wings. The man didn't open the package. He also noticed that there was a pattern specially designed by the sender on the parcel, which became his hope. Later, after he made an iron sailboat, he specially painted this pattern on it (which I discovered later, and this detail is worth noting), which further shows that he regarded the parcel as hope. Finally, he sent the parcel back to the sender (I think it's here)