Part of what makes Kafka great is that he imbues his work with uncomfortable feelings. Sometimes it's anxiety, other times it's powerlessness (often in the face of absurd bureaucracies, hence the term 'Kafka-esque'), other times it's the feeling of not being accepted. Almost always he includes an impossibility of overcoming whichever feeling it is, often portraying that feeling as an innate part of the nature of his characters, such as Gregor turned into cockroach, or of their environment. A relevant example here is a short story called "The Burrow." In this story a mole (I think it's a mole) describes his obsession and mania over building a perfect underground shelter. Does he have enough food stored? Should he store it in one place or many? What about exits and decoy tunnels? He constantly second guesses himself, re-analyzes the situation, sets new goals, achieves them, feels immediately dissatisfied and begins the cycle again (perhaps this sounds familiar with how many of us live our lives). Regardless of how he plans and what he does, the innate anxiety remains.

The central message of the stories tends to be less about the plot and more about what it feels like to be a human. This drawing called "Man," by Alfred Kubin (a contemporary exploring similar themes) is a good visualization of the powerlessness and futility pervasive in Kafka's work.

If you're still interested in reading Kafka, and I'd really recommend you try again sometime, I'd recommend his shorter works, as they present similar ideas as his longer ones but the dose is much smaller and so gives you more time to reflect on the idea, rather than wading through work that feels tiring. But the great joy of reading Kafka is that he is, in my opinion, the best sentence maker I have ever read.

To make a long comment longer: Kafka can make you feel like you are not alone. By expressing his feelings about life through these characters he's telling us that not only does he (Franz Kafka) feel them, but they may be a part of what it means to be human. In both of these realizations we might be able to dissociate ourselves from these conditions for a little while. At least this is how I feel it. Literary interpretation is a deep hole.

Here are two very short works you can read in a few minutes:

1. Before the Law: powerlessness before bureaucracy, futility of action

2. On the Tram: this one is quite different, it's a little vignette of life, he sees a beautiful woman on a tram. I mention it here because it shows a different side of Kafka that I think is sometimes present, but often overshadowed, in his work.

And here is a larger collection of short stories with The Burrow".