God gave the man a job in Eden, which was to cultivate and take care of it. Being in the Garden of Eden does not mean humans do not have to work.
However, the job seemed not hard but light, easy, and even authoritative.
The first rationale is found in Genesis 3. Verse 23 says that Adam and Eve were driven out of the Garden of Eden, and they worked the ground of the earth. Verses 16–17 describe that the ground was cursed because of the sin of Adam and Eve, and then it produced thorns and thistles. That is why people have to spend their whole lives in labor to earn and eat. It implicitly indicates that the work in Eden and the work in the earth are in contrast.
The second rationale is given in Genesis 2. The first job Adam did in Eden was to care for, observe, and name each creature. Generally, in the process of naming, the higher person gives the lower person’s name. Parents name their child, a king names a servant, or an owner names a pet. In the Bible, there are many cases in which God directly named His people, like Abraham and Israel. Adam did it in Eden like a king.
God gave the man jobs to do in the Garden of Eden, which were not only light and enjoyable but also authoritative.