it has done nothing of significant value for the citizens here.
That's a bold claim. I recognize that a significant portion of the population has fallen out (down) of the middle class, and I fully agree that we need to address that as a major problem. At the same time, you seem to be ignoring the roughly half of the middle class that has moved up into "upper middle". The typical H1B position is not going to someone who has fallen out of the middle class - it's going to someone who has a good technical education with modern skills. Those people are not the ones struggling at the moment.
If you allow a glut of cheap semi-slave Indian labor to enter the market
We are talking about an almost paltry number of people (less than 100,000 per year in a country of 160,000,000 workers. I think I could argue that H1B does not even have a statistical significance, but we are arguing on ideology, so lets have at it.
So here's the problem. You have signed a trade agreement which allows free movement of goods and free movement of capital. Capital that would normally have been spent domestically moves outside, and in exchange we get goods. But what happens to the workers who once made those goods? They certainly can't go to India to pursue those jobs. And Indians in sweatshop jobs can't say "screw this" and move to a nice US factory. We have artificially created an imbalance, and it is screwing with the free market. H1B is certainly not the only way to fix this (in fact, as I point out above it probably is not even having a significant effect) - but it is better than doing nothing. I think free trade is probably better for everyone in the long run, but I strongly feel that these agreements need to take into account things like ecological protections and worker standards. But I digress...
you're essentially advocating for the circumstances to push the middle class towards the lowest common denominator.
No, that's how you are framing my argument. My goal is to keep the US economy dynamic, competitive, and efficient so that it continues to punch above its weight and raises the standard of living for all.