All Christians, Jews and Muslims believe that God created the heavens and the earth, making them all "Creationists". Within the Christians, there are four groups of Creationists; you are referring to the Young Earth Creationists who believe Genesis chapters 1 and 2 show the Earth to be created on Day One, and they take that period to be 24-hour-Earth days. They then take Bishop James Ussher's chronology based upon the generations listed in the Bible to mean that humanity has been on the earth for 6,000 years, roughly.
But the majority of Christians don't agree with that. Some take the 'Days' to be periods of 1,000 years each, others say 7,000 years each. Most will tell you that they are indeterminate time periods because 24-hour-Earth days could not have arisen till Day Four. They also point out that the heavens and the Earth appear to have been created before Day One began. This would allow for the heavens and the Earth to be billions of years old, so the majority of Christians are in harmony with the scientific and geological evidence.