Maths is so much more malleable and abstract than what you think it is

No it isn't, as per Maths textbooks

You really do not understand maths as well as you think you do

says someone who doesn't understand it at all

just to be told “nope! That’s just how it is!” with no further thinking at all

Just as well I'm their teacher then, hey? 😂 I showed you the textbooks, and you refused to look at them

A lot of maths is chosen

Nope! Only the notation.

So long as there not being contradictions or paradoxes, the formulation of a form of math is valid

You mean so long as it obeys the laws of nature

Which is why you have different forms of maths with different rules

But we don't have different rules, only different notations. The rules of Maths are universal

And you really could use some more humility

says person who refuses to look in Maths textbooks

it’s obnoxious when you act all so high and mighty and arrogant,

says person who refuses to look in Maths textbooks

with no interest in questioning your assumptions

there aren't any. All the rules of Maths are explicitly spelt out in Maths textbooks, not to mention several of which are easy to prove.

Devolving into ridiculing the person you’re discussing with

Like the person who refuses to look in Maths textbooks

told clearly “I chose this.”?

No-one chose it. There are even several species of animals that know how to count! 😂 It's a universal law

You are making your arguments effectively unfalsifiable by just going “Nuh uh” all the time

Just as well I also provide the proof in the form of Maths textbooks. Oh wait, you keep refusing to look at them! 😂

Get some humility

says person who refuses to look in Maths textbooks

learn a bit about the foundations of maths.

says person who knows nothing about it. Makes up fanciful stories like it was "chosen" when nature proves otherwise

See for yourself what actually is the foundation

It's Arithmetic. Even some animals know how to do Arithmetic, none of them know how to do set theory! 😂

And, spoiler, it’s not a high school textbook.

That's right, it's a Primary school textbook 😂

Hopefully I do not need to tell you how concepts are simplified for younger students

And yet you still manage to not understand them 🙄

instead of overwhelming them with the complete knowledge of a subject

Welcome to why Algebra isn't taught until Year 7 😂