It got better.
This is precious
1) Snape’s writing easily could’ve changed as he got older. When he was a teen his writing is described as messy and cramped, so maybe it got neater as he aged and thus harder to identify.
2) No-one else guessed it was a broomstick, not just Harry. Besides, I think we all know that the apparent cluelessness of the students was there purely to make a more dramatic and affective cinematic moment, rather than them all being actually stupid.
3) There is no reason for Harry to figure out instantaneously that there is a Basilisk in the Chamber of Secrets. After all, he and the others spend over half the book thinking it was a person who was petrifying the students, not a creature. And he’s still getting used to life as a wizard at this point; there’s a lot he doesn’t know. He didn’t even know what parseltongue was at first, and why would he.
4) None of the main Ravenclaw characters come off as being intellectually superior to any of the other students. Besides, Hermione is smarter than nearly all of them put together, and which house is she in? Gryffindor.
5) I’m pretty sure Harry does think there will be a war, but that doesn’t stop him from asking Sirius’ opinion on the matter - either to gather more specific information, or simply to confirm his suspicions. It’s also a way for him to show Sirius he’s feeling vulnerable if not scared, and seek some comfort/reassurance from his Godfather, the closest person to family he has left.
6) And as for the rum spell….yeah I really don’t have any defence for that, that really was a derp moment for Harry. I dunno, maybe he couldn’t understand Seamus’ accent or something :/
This was still pretty funny though.