Human influence on the carbon cycle is actually very large and very detrimental to the planet. I will name some of the most important reasons for this statement.
1) By burning fossil fuels, humans increase the concentration of carbon dioxide in the atmosphere.
2) Man cuts down forests, thereby reducing the rate of absorption of carbon dioxide by plants.
3) Human anthropogenic influence leads to an imbalance in the carbon cycle, as a result of which conditions on our planet may change (because global warming is directly related to the concentration of carbon dioxide in the atmosphere)
4) Man pollutes the waters of the world's oceans, which also absorb carbon.