The typical manga plot made to make the readers think "just leave them to die for once!" only for the MC to do the same thing they ALWAYS do and save them and befriend them through some bullshit repentence/"I understand why you did it" drama...
Author crossing out the mandated trope situations already, doesn't bode well for future plot.
Would be nice with some manga where the plot stays interesting even after the first 20 pages. With chapters like this it's just "I hope there wont be too many filler chapters" and you read just one more chapter, and one more chapter...
I suppose since we're so deep in trope, you can explain to us the rest of this arc then, even before the next few chapters come out.
I mean, you're so astute, you even spotted that the author initially tried to hide that trope by making it seem they were people the MC would leave behind! I'm sure the rest of us had no idea...we were all taken in by the author's double blind attempt to make them appear like innocent people worth saving....
Jokes aside, maybe you should reconsider what's the problem here, the manga or your proclivities. It doesn't say "mystery" on the genre tag, and most manga is character-centric anyway, "plot" is just a tool for that. You predict you'll be inundated with "filler" but nobody's forcing you to read something you clearly expect to be bored with. I think most other people here know what the appeal points of this manga are supposed to be, avoiding tropes isn't one of them.
Which brings up another interesting point. Why did you feel the need to "invent" an element to amplify your disappointment in the author for resorting to said trope?
That out of the way, being reminded of Jelly's strength makes me wonder if it works the other way. Does having a brain to use, so to speak, increase the slime's ability to think? Her thoughts are still distinctly inhuman, but I feel like she's gotten much smarter and sharper. It doesn't just seem like the experience she's gaining along the way serving as learning material.