Retirement tax questions

But another confusion. I contributed after-tax money to the traditional IRA, so I thought I wasn't supposed to be taxed at all? 

 

Or is it that I received an undeserved tax break in 2023 (or should have, if I'd filed the right form, sigh) and now it's being cancelled out by taxing me? 

I'm so confused. I swear I'm a smart person in real life.