Are there levels of depression?

I don’t know about levels, just that the intensity can differ.
And the reason/source can be of importance.

Yes, there are various types and levels. It’s a vast topic.

Depression makes the entire world seem dismal and unsatisfactory—but it is far worse when coupled with anxiety.

When I was a teenager, I remember the deep depression following a break-up that may have lasted for years. It was painful enough for wailing. But even then, I never worried (anxiety) about my girlfriend/ex not having a home, or being homeless or unemployed. That kind of discouragement makes life totally debilitating.

Some depression can be cured or at least alleviated by physical exercise and / or accomplishing something. Other depression is so deep, you can’t do anything but blink and swallow hard and barely subsist in fear and sadness,

Can’t say how they are different, only as said above, differ in intensity and whether or not coupled with anxiety; or whether or not mostly chemistry related or from circumstances.

Yes, definitely. The diagnostic scales often classify patients’ symptoms as “mild”, “moderate” or “severe”. Here’s one of the most frequently-used evaluation scales. By adjusting the symptoms for your (imaginary?) patient, you can see how the intensity rises.

Many people, when they hear the term “depression”, would assume the patient is no longer able to experience any joy, stays in bed all day, unable to care for themselves, possibly at risk of hurting themselves. Those are symptoms associated with severe cases, often called “major depression”. They require immediate attention by a professional. Less intense forms of depression, however, can easily get worse if left untreated.

There is another type of depression that is called “persistent depressive disorder”. While it’s less intense, it lasts for much longer than the typical depressive episode and can be debilitating.

Here’s a short article on different types of depression.

As others have mentioned, there are different levels from a medical perspective. From experience, depression has the ability to present in such different ways, that it almost feels unfamiliar. Often, when you feel as though you’re at the “bottom”, depression can suddenly offer further depths of pain that you didn’t know were even possible. There are so many flavors. I’m currently savoring a deep, dark variety. But occasionally, a different flavor emerges, and it reminds me that there are non-depressive flavors.

* Depression also apparently encourages the use of incomprehensible and inane analogies and metaphors.

Melancholia is a type of depression of a different vein—once, thought to be a physical illness caused by too much black bile in the liver. It was classified especially as a women’s illness from the middle ages to the early 20th century but disappeared from medical books sometime in the mid to late 1920s.

Melancholia, for women or men, is characterized by longings for an idealized past, or pining for longings never fulfilled, or an extreme desire or need for something that cannot even be defined or known.

The feelings can be extreme and intense but I’m not sure if its medically or psychologically recognized.

I dont know. I’ve never suffered from depression.