I really like the diving bell concept, first I've seen this jam! The procedural nature of the levels and enemy/pickup spawns was a very nice touch and keeps it fresh every time. I see in the pictures there's an upgrade shop, maybe I just missed it but that definitely sounds like a great thing to have in this game, especially if the upgrades carry over after you're destroyed. My only major criticism is that it's not uncommon for you to have to shoot downward so much that you go off-screen at the top and lose sight of the diving bell. I think maybe if there was significantly less force pushing back on the y axis it'd make for more enjoyable gameplay. You could even explain it in lore as the pressure under the sea keeping you moving down!
Anyway, here's my gameplay video playtest of it. Hope it helps provide you some valuable first reaction feedback!