Compost works in three ways - first, the carbon is a natural soil builder; second, the nitrogen, phosphorus, potassium, etc. make it an organic, slow-release fertilzer; and third, bacteria, actinomycetes, fungi, protozoa, etc. work in the soil to feed your plants.
What works so strongly in compost's favour can occasionally backfire...
Sometimes, rarely, in fact, but sometimes, the life in the compost can get into our body. For the small number of bacteria that will hurt us, it can be a case of being in the right place at the right time. Recently, a lucky Legionella found its way into a gardener's finger and made the Scottish news, causing cautionary notes to be added to labels on bags of UK compost.
Remember to wear gloves when working the soil.