Even among the feasts the 7th day Sabbath is separate. The feasts are nature based as far as they are agricultural based and use the sun and the moon.
Whereas the Sabbath is not dependent on anything based in nature. It is totally detached from the world of space. It is completely holiness in time. At creation for the first 3 days there was no sun or moon yet they were called days. So on the 7th day we are called, to turn from the world of creation, to the creation of the world, and its Creator.
To some the Sabbath is just a day to rest to renew our strength to get back to work. But the Sabbath is not to rest to renew our strength for more activity, so much as it is just for the sake of Life itself. Man is not a beast of burden. The love of the Sabbath is the love of mankind for what they and God have in common.