There's 4 people in the entire world at the time..adam,eve ,Cain and Abel and the Lord your God commanded offerings?
Jonah's reference counters your assumption that you should love God from the heart and not obligation. Did you think Jonah loved him from the heart or was he not compelled ?
Get the difference?
I believe we can all jump to assumptions taking bits and pieces of what we read. I would not assume there were only 4 people, being that Cain stated
Gen 4
14 Today you are driving me from the land, and I will be hidden from your presence; I will be a restless wanderer on the earth, and whoever finds me will kill me.”
15 But the Lord said to him, “Not so[e]; anyone who kills Cain will suffer vengeance seven times over.” Then the Lord put a mark on Cain so that no one who found him would kill him. 16 So Cain went out from the Lord’s presence and lived in the land of Nod,[f] east of Eden.
this seems to me that there were more people on the Earth than those in the story of Adam and Even and Cain and Abel