No, Theravada is not a system of direct realism.
Realism is the belief in the following three propositions:
- Objects precede consciousness.
- Objects exist independent of consciousness.
- The world of objects is the real and (more or less) permanent one.
Materialism is a subset of Realism that adds the fourth proposition:
- Consciousness is dependent on objects.
Idealism is the belief in the opposite for all four propositions:
- Consciousness precedes objects.
- Consciousness is independent of objects.
- Consciousness is the real and (more or less) permanent thing.
- Objects are dependent on consciousness.
Theravada proports that consciousness and objects co-arise. Neither precedes the other, neither is independent of each other, neither is the real and permanent thing. They both are dependent on each other. There are no objects without a consciousness to view them; there is no consciousness without an object to direct itself toward.
Everything is namarupa. Objects are just form (rupa). Form is beheld by the mind. There is no external object you can point to; there is only a mental image of form that can be pointed to. Any assumption or belief that a form is an external object that exists in the world independent of you is just a belief that appears in the mind.