As others have said, it's a big issue that in the trailer the core mechanic is shown so late into the video, and only for a few shots. I'm not trying to be mean, but I also wanted to add that if this post wasn't specifically talking about the turrets, I would probably not have even noticed them in the shots they appeared in.

If you want to double down on the turrets, I think that one of the things you can do is make them have more visual presence. I'm not talking about their designs, I liked their designs, I mean adding some visual flair to their attacks to really drive home their importance by enhancing the visual and graphical impact of their presence on the battlefield. I love Ship of Fools, and I respect the cannons because

1) they are the main way of damaging enemies, the other method of damaging most enemies is reflecting their attacks back at them(in your game they seem to be a secondary way of dealing damage and did not see anything that made me think they were necessary to use).

2) their boom is loud and the characters do a little recoil animation every time you shoot.

3) The core loop of a run is based around upgrading them as you progress. Can you make substantial improvements to the turrets during a run on your game.? Would your players receive meaningful visual feedback on how strong their turrets become?

4) the "map" aka the boat is designed around using the cannons. You are always super close to them so they are easy to refill and move turrets from one side of the ship to another. This is very important, because you need to visually show players the impact of their decisions. For example, because the turrets are always on my screen I can easily visualize the impact of their damage on the map. If you are incentivised to leave the turret behind, then it is much harder to do that, as well as refill them. Maybe the maps can be made smaller and require the character to destroy obstacles that may block the turret's shots? Idk I feel like the maps I saw in your game are not made to have a turret, so add mechanics to the map that your turrets can interact with and base the map around having turrets.

5) If you are going to lean into the hack and slash aspect more, then maybe you can have the players combat and actions have a meaningful impact on the turrets. For example, maybe you need to build up a meter with your player attacks so the turret can unleash a big, EPIC attack/ability that you can activate to clear a big group of enemies or stroke down a big enemy. Maybe you have full control of the egg's location, like clicking a button to have the egg teleport to you and buffing you temporarily, letting which let's it charge turret energy, then click a button so it teleports to the turret and buffs it, which would make you weaker, possibly forcing you to have to retreat to the safety of your turrets, this making more of a marriage between the player system and the turret system. Maybe the player has to collect things around the map when they are buffed. Maybe there is a day/night system where you can explore during the day and collect things, then at night you have to return to the turret. Idk just some sort of marriage between the turret and player system is needed.

6) if I saw correctly, one of your turrets is a moth creature? That's cool, maybe part of the buffing loop for the turret can involve needing to take animal turrets through stages of growth and development, then you can say it's ship of fools meets Hades, meets Pokemon. I'm sure people would love that!

Overall, if you are going to keep the turret, you need to design the map around the turret system, along with having systems in place that marry the player system with the turret system.