Final answer:
An animal with primitive movement and a nervous system is likely an invertebrate, which encompasses animals without backbones and with varying complexities of nervous systems.
Step-by-step explanation:
An animal with primitive movement ability and a nervous system would be considered an invertebrate. Invertebrates are a large diverse group of animals that lack a backbone. While they have a nervous system to sense and respond to their environment, their nervous system can range from a simple network of nerves to more complex structures including brains and several different sense organs. Among the variety of nervous systems observed in invertebrates, for example, jellyfish possess a 'nerve net' and octopi have sophisticated structures with specialized lobes, indicating that the complexity of nervous systems can vary widely within invertebrates. Furthermore, invertebrates have an innate immune system but generally lack the adaptive immune system that is found in vertebrates, suggesting that the innate immune system is the more ancient of the two, having evolved first.