Jonah 1:9

And he said to them, “A Jew am I, and before the LORD God of Heaven, who made the sea and the land, I revere.”

And because all these questions were trying to determing who had sinned and what the sin was, Yonah was able to succinctly answer all with "I am an Ivri and I fear Hashem, Gd of the heavens". Meaning, you asked my sin and whether it was related to the land or my nation or whether I sinned in a way that would make me deserving of death, now see that I am an Ivri. The word Ivri both being from the land of the Ivrim but also that he was "ovvar" disobeying the command of Gd as it is used in (Bamidbar 14:41). This explained nature of his sin and also against whom he had sinned (Hashem, Gd of the heavens) and you dont need to inquire about my land and people because I didn't sin before you but only before Gd whom I fear and the matter isn't in the realm of the heavens but in the Gd of heaven and earth who created the sea and the storm and the dry land that we cannot reach.

A different explanation is the sailors asked "who caused this wickedness for us" meaning if it was a decree from heaven on his birthland that he would need to drown in the water or was it Divine Providence. So they asked questions to get more information. And it wasn't four separate questions like it seems in the pshat, but instead the questions were as follows: What is your work? What is the work that because of it may have cuased you to be punished this way. And they didn't say how did he sin in his work because maybe his punishment would have come on account of others from his land and the wickedness of his nation. And what nation are you from that would make you culpable...? and SImilarly all the questions were on this track or trying to figure out why he was culpable. So Yonah answered about the work that he was an Iviro... menaing the matter doesn't have to do with my land or my nation but I am an Ivri and you know the land of the Ivrim is a good place and the people who are there travel the sea without issue. But I fear Hashem, Gd of the heaven who looks down from His place and puts His Providence on the land. And I fear Him because not only did I sin but He created the land and the sea and everything is in His Hands like clay in the potters hands. And this is why Yonah's answer to the sailors questions made sense.