I've participated in 5 game jams now, and I've only managed to submit to 3 of them. One of those submissions was totally a prototype and unplayable. I feel like it's super natural to run out of time and I've definitely learned over time it's better to keep the scope of what you want to complete small at first, then add more features as you reach your goals incrementally.
For example for this jam I had a bigger vision for my game to have roguelike mechanics with a level progression system and upgrades, but realized that was thinking way too far ahead and instead I chose to make a simpler version of the game and focusing on the core mechanics instead. If I had finished that faster, I would have then had the time to think about how to add more depth to the game, but I could still submit a finished product if I didn't get the chance to dev more.