I don't think it is necessarily true that the hero fails, or that he finds vitality in it in Kafka's work. In The Trial, our hero refuses the struggle (the opposite of vitality in it!) and gives up, dying "like a dog" in his words. In The Castle, our hero diligently tries to play the game but again finds the opposite of vitality in it; his status is repeatedly degraded. His status at the end is still indeterminate but he remains hopeful.

I think in general that if you think you've summed up Kafka with a sentence decisive enough that you can accuse others of resisting his message, then you probably prefigured your interpretation with the biases you brought into your first reading of him.