I think the concept is great and the execution is incredible. I love how the music changes as you switch between the past/present timelines, it really helps sell the fact that the timeline has changed. Also great job with hiding objects that are out of view of the character, the line of sight issue with top-down games is an infamous one and I think your solution works perfectly for your game. I think the only suggestion I would have is to make it a bit quicker for switching between past/present, as there were times that I would be trying to switch between in order to attack an enemy but it would take too long and I'd end up taking damage(although this might just be a skill issue on my part, I could've dashed away/backed up and probably been fine). Overall a great game and incredibly impressive for a jam game, especially it being your first.
Edit: I remembered another suggestion for future jams: it's nice when games have an option to skip to the end of each dialog piece, allowing the player to ready the whole text without having to wait for it to all show up, so perhaps adding that in future games would be good and hopefully not too difficult depending on your dialog implementation.