Can there be zero taxes in retirement

Hello Experts,

 

This may be silly/stupid question but just wanted to do a quick sanity check 🙂

 

Let's say during my retirement, I withdraw $80,000 per year from my 401K.  Please assume no other income.

With this - my taxable income would be $80,000 - Standard Deduction($25K), this will leave us with net taxable income of $55K.  Would be this $55K considered as regular income and taxed accordingly OR it is considered as long term gain?  If the entire amount is considered as Income (not LT Gain), I am wondering how is that reasonable, since some part of that withdrawl could be gains out of investments? No?  I am sure, I am missing something obvious, please help!