Final answer:
The protagonist of The Tempest is Prospero, and his main challenge in Act 1 is regaining his dukedom.
Step-by-step explanation:
The protagonist of The Tempest is Prospero. In Act 1, Prospero's main challenge or obstacle is regaining his dukedom. After being banished to an island, Prospero seeks to regain his power and authority as the Duke of Milan. This is evident through his use of magic and manipulation to control the other characters and ultimately achieve his goal.