Buddhism was originally a medicine, not a religion
Buddhism is now practiced by many people as a religion, but it originally emerged from a misunderstanding of something that was not intended to be a religion.
The founder of Buddhism, known as Shakyamuni, was not a religious figure.
Shakyamuni was more like a doctor who discovered methods of meditation and their medical benefits, and taught them to people.
However, his teachings were so advanced that people eventually could not fully understand them, leading to the misunderstanding that Buddhism was a religion.
This site explains parts of Shakyamuni's original teachings, which are not religious in nature.