So long as everyone has the choice of where they are employed, slavery can't exist. Working for free is not slavery.
How does a minimum wage make a strong middle class? The only thing it does is devalue the dollar and increases inflation. Nothing more. We have a finite amount of resources, raising the minimum wage doesn't make more resources appear.
It wold take a long post to say more to educate you on this, and sorry to say, your reaction doesn't suggest to me you would get it if I did.
But a couple points.
Money isn't real. It's an artificial construct used to get an economy working, and it determines who has more and who has less, but it's not real other than people agreeing to pretend it is.
There is a distribution of wealth. Some 'real', some money,all the same for measuring it. It has higher and lower concentrations of wealth possible.
Increasing the minimum wage gives more to the bottom, redcing the concentration of wealth. It has negligible 'inflationary' effect in any moderate application (or even not so moderate).
It also has, as I said but yoiu did not seem to hear, benefits to the economy as well.
Finite resources? I'll repeat what I've said many times (wish I had a cut and paste):
Wealth is fixed at a moment in time (with different distributopns), and flexible over time (grow fast, grow slow, reeduce, whatever).
Too high a concentration, and too low a concentration, both result in less growth. Increasing the inimum wage when the concentration is too high, as it always is in the US so far, increases growth.
It also has the moral benefit of reducing the concentration of wealth below extremes (now) or excesses.
You pay the poor more. It reduces povery. They spend more, creating more opportunities. They get better education, they have less crime, they buy more houses. The rich get a smaller slice of a bigger pie.
If the rich are idiots, they demand a bigger slice of a smaller pie and exploit the poor more instead.
As for your first pont, tell it to the impoverished masses who worked in slave-like conditions or starved, and had that as their 'free choice' in the late 19th century or in many third-world oligarchies.
But as I said, I doubt you are getting this, so no point in saying more.