The work involved is awe-inspiring but WHY — with this much effort something wholly new and original and most importantly.... SAFE from copyright lawyers could have been put into the universe.
Sometimes "true" wholly original creativity can only blossom after people cut their teeth by experimenting with fanworks. Few people truly start with their magnum opus.
It's also the case that most successful mass market "original" works are thoroughly inspired by other work and exist as careful synthesis of influences with bits of inspiration and new ideas worked in.
Yeah. Pretty much any writer, painter, musician, or performer, will gladly tell you that, when they started, they were really doing something in the style of X as best as they could. In some cases we even have proof (youthful manuscripts, recorded schoolplays, early works). That's effectively fanwork. It takes time to modulate one's original contributions to any art.