healthy person
A straightforward noun referring to a person in good health. Often used in medical, lifestyle, or comparative contexts.
Healthy people are less likely to get sick.
This survey targets healthy individuals.
健康 is the abstract noun 'health' or the adjective 'healthy', while 健康人 specifically refers to a person.
Compound of 健康 (health) and 人 (person). The exact historical derivation is uncertain, but the word follows a common Sino-Japanese pattern for describing types of people.