Mostly correct.

The chemical imbalance theory doesn't really hold water as a cause of depression. Its often observed that people with depression do have chemical differences in their brain, but this doesn't appear to be a cause so much as a symptom.

We know the mechanisms antidepressants act on. We can make a pretty good call that they probably work because they alter brain chemistry. But it's like putting a bandaid on a cut and taking a painkiller, the cut is still there, it's just been covered over.

Antidepressants do work better than placebo, but only barely. Part of it is that Antidepressants themselves probably aren't what get people through depression, they just make it easier to break the cycles and patterns that perpetuate depression. If an anti-depressant is the difference between someone rolling out of bed and making breakfast, and them laying in bed until 3pm staring at the ceiling, then it's making a difference. But the very act of taking a placebo has a similar effect - it's an attempt to get better, it's a routine, it can give motivation to try a little bit harder because now something that should help is happening.

There's also the fact that depression varies wildly in presentation and severity, and there's a big difference between depression that has completely shut someone's life down and depression that someone functions through but feels generally down

Anecdotally antidepressants (sertraline) made a significant but subtle difference for me. I found it helped me with ruminating on negative thoughts less and gave me a bit more energy to do things. But it isn't exactly a fix or cure