Modern creationists (unlike before) believe in what they call "microevolution" - they think that diversification does occur, but there is some sort of barrier between "kinds". They cannot establish what "kinds" are; pretty much the only thing that they agree on is that there is nothing else in the human "kind", and that there were few enough kinds that you could fit them all on the ark (and that the former "kinds" could live and eat almost anything). The process of debating over what is in what "kind" is called baraminology.
Note that this really amounts to hyperevolution, given their time scale.
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"Illuminant light,
illuminate me."
™ Version 4.2