you can't equate evolution to something like the standard model bc there are so many things about evolution we still don't know because it happened a billion years ago.
Well evolution certainly happened in the past. But it's still going on to this very day. And will continue going on in the future.
Scientific theories explain how things work. To give you an example, we can use the theory of gravity to explain the orbital mechanics of our solar system. But me simply saying, "well we don't know what the solar system looked 4 billion years ago - therefore the theory of gravity is incomplete" - is not a valid premise.
Because scientific theories are not bodies of knowledge. Rather, they are a tool we use to get knowledge. They are a way of thinking. Scientific theories are a way of explaining and making predictions about the phenomenon we observe in our universe.
Or, to put it more concisely - they describe how things happen. And in the case of evolution - it describes the process of speciation through genetic mutation and selection. It describes how species change over time. Not every event along the way.