Hello Carico, welcome back.
Since nobody else has posted much to this thread, let me start. And I want to start by explaining what is a theory.
Let me start by talking about the theory of gravity. I'm sure you have heard of it. One of the things that the theory of gravity allows us to explain, is how the earth moves around the sun in an elliptical orbit. Apologies if this looks like a diversion. But I would rather start with a theory that you probably accept. Then I'll comment on the theory of evolution later in this message.
On the theory of gravity
Strictly speaking, the theory of gravity does not tell us anything about the sun or about the earth. The theory is about process that exist in nature. Those processes would exist even if there happened to be no sun and no earth.
When we measure some facts about the sun and the earth, we can use the theory of gravity to compute how the earth should move around the sun. A good way of describing this is that the theory of gravity allows us to interpret data (measurements) and use them to make useful predictions.
Scientists are often sloppy when they talk about theories. They often say "the theory of gravity tells us how the earth moves around the sun". However, strictly speaking, the theory doesn't say anything about this. It should be "the theory of gravity, together with some measurements of the earth and sun, tell us how the earth moves around the sun".
I hope you can see how it is often convenient for scientists to be a bit sloppy in what they say. Unfortunately, that sloppiness can be confusing to non-scientists trying to understand what they say.
On the theory of evolution
The theory of evolution is about processes, and how they are involved in changes in biological creatures. Believe it or not, but the theory of evolution does not say that apes evolved into humans. That's because it is about processes. The theory itself would be just as valid even if there were no apes and no humans.
We use the theory of evolution to help us interpret data and make predictions. In this case the data is what we know about species that exist today and what we know from fossils. The theory of evolution can thus tell us how anxient species could evolve into modern species.
Most scientists believe that humans evolved from apes. People will sometimes say "the theory of evolution says that apes evolved into humans." But, strictly speaking, the theory itself does not say that, since it is only about the processes. A better statement would be "the theory of evolution, together with the known data, implies that humans evolved from an earlier species of apes."
Strictly speaking, even that last statement is not quite right. The problem with it, is that we have too few fossils to fully map out the origin of humans. The evidence that humans evolved from apes is very strong, and no evolutionist doubts it. But it actually does fall a little short of proof. There are currently at least two (probably more) hypotheses on the evolution of humans. According to one hypothesis (the Aquatic Ape Theory), humans evolved from a species of aquatic apes that lived near the shore and probably used fish as the main diet. The other hypothesis is that a band of apes adapted themselves to living on the savannah instead if in the forest, and humans evolved from these savannah apes.
I think the majority of evolutionists think the aquatic ape hypothesis is very unlikely, and the way we evolved is more likely to be along the lines of the savannah hypothesis. I mention both of these hypotheses only to indicate that the exact path by which humans evolved is uncertain.
The main conclusion is that there is still some uncertainty on the history of human origins. However, we do know that modern humans have been on earth for far longer than the 6000 year age that some creationists claim. There are fossils of modern humans, and there are human artifacts which are significantly older than that.
Enough for now. Unless somebody beats me to it, I will later post something about the processes of evolution, and about how it might have happened.