You have misunderstood several things, including the general definitions of creationism and evolution.
Creationism relates to how life started, and many theologians who believe in creationism (i.e. that life was started by an intelligent force) also accept that life then evolved over billions of years, due to the overwhelming evidence for this.
However, the Theory of Evolution by Natural Selection does not state there is a law that a species MUST evolve. A species only evolves where a mutation gives an individual an advantage within its environment and therefore a better than average chance of surviving and passing on its genes to the next generation. Mutations are random and therefore most mutations do not give an advantage, so most don't lead to evolution.
It is no surprise at all that relatively simple organisms like bacteria are surviving in very similar states to those that existed 1 billion years ago. At least you accept that life has been around for at least that long! It could be that they are direct unevolved descendents, or that they have evolved from a different sub-branch of bacteria to fill the same niche.
Finally, as I'm sure you are aware, there are many, many examples of fossils that do display evidence of evolution. And there will be no mammals or other vertebrates in the same strata as your 1 billion year old bacteria.
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