The answer to whether humans are causing sixth mass extinction is a yes and we don't really need scientific data to know that.
Human activities have lead to grave changes to take place on the planet, which has affected both the flora and fauna .
These changes in the nature can lead to mass extinction events.
According to Britannica, a mass extinction event is "any circumstance that results in the loss of a significant portion of Earth’s living species across a wide geographic area within a relatively short period of geologic time".
The reason for mass extinction events can range from a number of volcano eruptions, comet and asteroid impacts, and climate changes.
Ordovician-Silurian extinction, Devonian extinction, Permian extinction, End-Triassic extinction, and finally Cretaceous-Tertiary extinction are the five mass extinctions in Earth's history.
Human activities have already created the ground for a sixth mass extinction event. And many scientists opine that we're amidst a catastrophe.
The current rate of species loss ranges between 100 and 10,000 times the background extinction rate, which indicates to a mass extinction.