I genuinely wanted to complete all the levels. It wasn't always clear what you were supposed to do, but I managed to complete some of the trickier ones by pushing the barrels around to block the AI's line of site. Even if that wasn't the intended way though it still felt fun to do.
I actually completed all the levels - reading my comment again, it sounded like I didn't finish. That said, certain levels felt awkward to complete; like I had to hack my way through them rather than use the mechanics as they were probably intended.
For example, to beat the level below I pushed the top barrel onto the first enemy so he couldn't see me. This also prevented the second enemy from seeing me when I jumped to shoot the barrel through the slit. In the end, I never figured out what the purpose of the first flaming barrel was...
Your solution was actually the intended solution. The exploding barrel didn't really have a purpose - which was an oversight on my end, my bad. I'm glad you finished the game though! I'm actually thinking of polishing the game up and putting it on itch - so your feedback on the level design helps. Thank you :)