I would use teleporters, which can be more interesting (seeing as it’s not all jumping up).
You could also add multiple different paths/ways to go, and then can intertwine and connect at various places (I added that in one of my platformers and I got good reviews)
You could add an item of sorts for the user to collect (For example: You can hide/place various gim fish around your map for the user to collect, and at the end they get a reward of some sorts)
There’s nothing wrong with using sentries in my opinion, but I get that you may not want them or they may not appear professional enough for you. Its your game you don’t have to add anything you don’t want to 