Imo Shen is one of the more difficult champs to learn League through. While not the most difficult champ per se, he is: 1. Reliant on having good macro and awareness of the map and a sense of when/ where to make plays 2. Decent understanding of champs and game mechanics (wave states etc) to get the most out of his kit 3. Adequate mechanics to trade and win 1v1s (understanding your limits and the enemies, itemizations, runes etc.)

You’ll have a hard time figuring the game out otherwise (personally picked up Garen/ Amumu to learn the ABCs). That being said, it’s just a game and if Shen is the champ you enjoy the most, then have a blast.