One interesting approach showing delight from Torah is actually nature starts from the idea that the neshama that Hashem implanted in us comes from a high source, as Chovos HaLevavos (Sha’ar Avodas Elokim 3:2) explains (quoted here)
When Hashem created man, He joined two distinct elements to form his
living soul. These are his spiritual soul (what we call his neshamah)
and his animal soul. The conscious “I” that thinks and feels is made
up of both parts. The neshama comes from under the throne of Hashem's
glory. It is pure and lofty, holy and sublime. All that it wishes for
is that which is good, proper, and noble. Because it comes from the
upper worlds, it derives no benefit from this world and can’t relate
to any of its pleasures. The other part of man’s soul is very
different. It is exactly like that of an animal, with all of the
passions and desires necessary to keep it alive. That is his animal
Just as the body needs food to live and grow, the neshama also needs "food". There are sources that write the food of the neshama is Torah. As such the joy from learning Torah would literally come from feeding the neshama with its expected nourishment.
Two sources I have found so far on this are
Since through the knowledge of Torah the Torah is absorbed in the soul
and intellect of the person and is encompassed within them,it is
therefore called the “bread” and “food” of the soul. [...] through the
knowledge and comprehension of Torah by the soul of a person who
studies it well, with the concentration of his intellect, to the point
where the Torah is grasped by his mind and is joined with him so that
they become one, [the Torah thereby] becomes food for the soul.
(Tanya chapter 5)
Wisdom is demanded by the soul as the food is demanded by the body.
(Ibn Ezra on Isaiah 55:1)
(see also the introduction to Mishna Berura, at length)