Health insurance mainly refers to critical illness insurance and hospitalization insurance. Hospitalization insurance is generally short-term insurance with annual payment, but it can be automatically renewed. Critical illness insurance is life-long health insurance, which generally takes long-term payment.
You asked, "Why short-term payment?". If you buy critical illness insurance for the sake of disease protection, it is best to pay for it for a long time, so everyone's choice may be different.
Further reading: How to buy insurance, which is good, and teach you how to avoid these "pits" of insurance.