Thanks for sharing your experience! It'll make the team happy to hear.
It is definitely very linear. If we ever expand this into a commercial offering, I think it would be a more engaging experience to include elements of exploration. In the context of this game jam, we were very intentional about being story-first, so we made the decision to make a Linearvania (more Metroid: Fusion than Hollow Knight) so we had enough time to polish each narrative and setpieces as much as possible without also needing to deal with the complexities of open world design. Things like iconic lock-and-key locations to aid in recall after receiving a new ability, avoiding game-wrecking sequence breaking, an actual map or some other form of orientation, filling the world with meaningful and interesting things, etc., are design problems that take time to solution and I know I wouldn't be able to solve well in the time that I had on top of everything else.
We definitely could've made an exploration-heavy Metroidvania, but it would've come at the cost of the narrative and setpieces, which is where we wanted to focus on this project. Alas, can't get it all in in one month. :')