In a similar style are:

Captain Underpants

Dogman

Ook and Gluk

Some fart joke level stuff, but generally wholesome.

Screen them first, checking out a library copy.

Also, the Sid the Science Kid series is very wholesome. They have a bunch of books released too

Have you ever run across Beverly Cleary?

The whole Henry and Ribsy run, as well as the Ramona and Beezus stuff is definitely old. So it has an archaic feel to it. Hell, it has that feel back when I read it all the first time as a kid forty odd years ago.

But it hits well. I've read it to various kids over the years to good effect because it's simple, easy to follow, and easy enough to relate to for most kids. It won't hit for every kid, but it's where I tend to start once they're past Seuss.

Edit: the Wikipedia page https://en.wikipedia.org/wiki/Beverly_Cleary

It reminded me of the Ralph S Mouse stuff too.

Hi Dave

Our 9 y/o girl is really into Wings of fire at the moment - nothing like Wimpy Kid sorry.

You 11 y/o (another girl) has developed an interest in Asian tween graphic novels, moving on from wimpy kid, but I see that she still has one on loan atm.

Sorry that I cant offer something better

I didn't realise our kids were so close in age

Aliens Ate my Homework

Sideways Stories from Wayside School

I loved both of these when I was that age.

Another vote for "Captain Underpants". It's immature and strange and great.

I know it's not related in tone at all, but I loved the Redwall series as a kid.

The Notebook of Doom - good series, there is a short spin-off, but I don't remember the name. A little spooky at the start, but should be ok for 9yr old

The Alien Next Door - okay story. Not a long series, but fun enough

Magic Treehouse - pretty sure you know this one, but I haven't seen anyone mention it on this post

My now 10yo loved all the Enid Blyton books a few years ago, especially the famous 5.

I'm not gay, Greg

Gonna second the Captain Underpants recommendation. And when I was that age, I really liked Deltora Quest. It's more of an epic fantasy adventure for kids than jokes, though.

I was obsessed with the Series of Unfortunate Events books around that age. They can be kinda dark as far as kids media goes, but I don't remember them having any of the weirdness you described with the Wimpy Kid books.

Haven't read them since I was a kid so not sure how they've aged but I really liked Encyclopedia Brown.

The 13-Storey Treehouse series.

There are a lot of good suggestions here already, my kid never got into wimpy kid, but is a bookworm, about to turn 10. Some books we've liked; (with Mild summaries written at 6am)

Minecraft woodsword books is about a group of kids that go in and out of a VR Minecraft game

Harry Potter (you can dislike the author and still like the story)

Percy Jackson is about a present day Greek demigod, growing up.

Hotel flamingo is about animals working at a hotel

Dragons of wrenly
Puppy place.
Storm dragons.

Silver arrow (train story)

Not a parent, but hear really good things about Bluey. Other decent shows for that age range would be Daniel Tiger or even the original Mr. Roger’s Neighborhood.

Those shows are typically for younger kids , so if looking for something that will appeal to a pre-teen, Reading Rainbow is a classic that can get kids into actually reading books, along with Between the Lions (though that one might be for slightly younger than preteen).

I would also say that the early seasons of Cyberchase are great for math and science concepts and Arthur is a great show all around and has tons of episodes.

Most of these are older shows, but they should be readily available on Internet Archive or YouTube and try to be low stimulation with good role models rather than high stimulation with bad role models.