Survival is a selector, not an engineer. Variability around the genetic norm means several closely related forms existed or were coded to exist— not that new genetic material was added. Survival could not engineer new species.
Survival could however select for the creatures best “engineered” for changing environments. Engineered, I understand, supposes that an “engineer” designed and built the creature. I don’t mean that. What I do mean is that “design improvements” have often been the unintended result of evolution ie. teeth gradually replacing the shell like “teeth” in fish over time. Over time, you can follow an amphibian to reptile and mammal like reptile to mammals and dinosaurs. It happened through incremental steps over long periods of time. A million years is a long time and a lot can happen over that period. We’ve only been around in our current form for some 200,000 years and preceding species very similar to us go back 2.6 my. Before that is still unclear exactly who is in our line though we can have a good idea but not proof currently. We find more fossils and things become clearer.