Nice work! I did a quick recording of my playthrough in case it's helpful to watch: A Burglar at the Beach by Mega-E | Cap Recording
I had fun trying to steal all the things and sell them, I also really like the art style and color palette you went with. I also really liked the sound effects, especially the being spotted 'oi' 😆
It took me a while to understand that I needed to go behind the rock to be safe from the seagull, and with it on the opposite side of the map, I found it really difficult to go between collecting bags and fearing for my life. I also had a few instances where I was running a bag to the shop, and someone spawned right in front of me for an instant loss.
I think this is a solid foundation for a game, and could be fun to play around with some of the difficulty tweaks. Some ideas like having more rocks available across the map, having a way to show how far from the seagull spawning once the exclamation point is shown, or being able to drop your held item if you have a 'uh oh I'm not going to make that' feeling when trying to bring stolen items to the shop.
Overall a really cool game, well done!