A god decides what will happen to people and sends word. The chameleon is given the message that people will not die. A second animal, usually a lizard, is sent afterwards with the opposite message, or sets off on its own initiative. The chameleon walks in its own manner, slowly, stopping, swaying; the lizard runs. The lizard arrives first, the wrong message is delivered and accepted, and death becomes permanent.
Versions of this are recorded from the Zulu, the Ngoni, the Bechuana, the Akan, the Yoruba and many others across sub-Saharan Africa. The casting varies, the reason for the chameleon's delay varies, and in some versions it stops to eat. What does not vary is the structure: death enters the world through a delivery failure, not through a sin and not through a punishment.
This is worth stating plainly because it is unlike the account most readers will bring. There is no disobedience, no forbidden thing, and no fall. Death is a clerical error at the beginning of the world, and no one is at fault in a way that requires atonement.
The story explains the animal as much as the animal carries the story. A chameleon does move like that, and the association with the delivery of bad news attaches to it in ordinary speech and in attitudes toward the living animal, which is often avoided.