Yep, the Dungeon Clear screen is the end of game (for now ;D) The gameplay for this is meant to be 10-15 minutes as it's just a vertical slice :)
When originally testing the first iterations of the game we didn't have the hookshot reset your jumps, but we heard a lot of feedback about how fun the hookshot is, so we decided to change it to be this way. Though we'll have some internal discussions about it, because some of the designers disagree with how powerful the hookshot seems to be.
Thank you for the rest of the feedback, and thanks so much for playing our game!