In the Berserk manga, what was the interpretation when Guts was lying on his back looking at the starry heaven?
To my knowledge, there is no official interpretation of the symbolism behind this scene. Your interpretation is a good one and might be exactly what the author intended.



My interpretation is different. I see the sky as a symbol for limitless opportunity. The sky goes on forever and there are countless stars, just as human potential for growth is limitless and there is no limit to the number of paths we can take in life.

I took this interpretation because in the same scene, Guts asks the same question twice in a row: "Where should I go?". The repetition indicates the importance of the phrase.

In other words, the sky represents the endless destinations and possibilities that exist in human life, like bright stars against a black nothingness.