Why aren't any of the school mums ' normal ' ??

Top tip - arrive at school as the doors are opening and the kids are being flung out. Get yours and go. No need to have to talk to anyone.
I did this for years (I also worked at the school so it was always timed to perfection!).
I had enough friends elsewhere and didn’t need to scope out anyone based on the fact that we happened to have had kids at a similar time.
I’m sure loads of the parents were lovely but I just cba with small talk.

I would find it easier to navigate a moon landing than "hang around" with other school mums. The conversations I over hear are appalling. They are so mean about each other. I'm happy to keep myself to myself.

Ours are all seemingly Stepford Wives.
Like 90% if them wear the same clothes of high end dark colour sports leggings, expensive light/neutral hoodie, in the same black cars that are 2022 or newer SUVs, holding beige Stanley mugs, pushing the same brand of buggy for their babies etc.
They all seem to be "kept" women. All very similar. All seemingly in their way to the gym.
Or often found inviting each other to the local gastro pub for brunch/lunch after dropping kids off

It's all a bit eerie.

and then there's me in my 2010 blue Vauxhall and just wearing casual office wear and no beverage in sight

Why do you have to “hang around” with anyone. You only see for a few minutes a day.
Hang around with sounds like something a 13 year old would say not a fully fledged adult.

"There are a few moms I've got to know that haven't tuned out like this, thankfully"
Spend time with those mums.

Maybe try meeting friends in other places than school?
What are your interests/hobbies?

Isn't it the same with anyone when you're getting to know them OP? We meet people from all walks of life, we think they seem nice, so arrange to spend more time together, until we decide whether they're really 'our' people, in which case it's possible you become life long friends, or, we find out that we disagree about things that actually matter to us, and then decide that they're not good friendship material after all. You are obviously spending a lot of time in the playground at the moment, so they're the people you're meeting, but equally, if you worked in a large company, or a school, etc., you might find that of all the people you got to know, there were actually very few that you would want to spend a LOT of time with.

You're there to pick up/drop your kids. Why worry about anyone else doing the same, they have nothing to do with you?

I think it’s hard when the only thing you may have in common is having children! Doesn’t mean their wider interests or views are the same as yours.
I have met some I get on well with but have largely focused on maintaining other friendships - old school/uni friends and work colleagues who I have more in common with..

I think op that mum friends can be difficult because the ONLY common factor you have that connects you and puts you in each others paths in the first place is the fact you both have kids the same age. So you're not connecting over your own hobbies/interests/values etc you're sort of just thrown together because your kids have been thrown together and you're trying to make something work organically that isn't really that organic. Like think of all the people you've come across in work or life who you've not bothered taking a friendship further with. Because you're doing those things for yourself rather than for your kids to have connections. I think you just do what you're doing - be nice and friendly to everyone and time will tell if they're worth continuing to invest in.

The only way that you can really begin to see a person's real character is by spending time with them. I don't think that there is any way around that. I once was getting to know a woman, and the same thing happened, that she made a very uncalled for comment about someone that I felt was unkind. I did not say anything, I think I was rather taken aback by her spite tbh. I just distanced myself from her.