That is the "theory" part. We have millions of facts, such as the ones I just posted for you. From these facts we establish and test hypotheses. The hypotheses that pass the test are supported, and can be brought together into a theory. Repeated tests, if passed, lead to a well-supported theory, such as the theory of evolution.
Now, one part of the theory process is interpretation. We organize the data and we interpret the data. The people who know the data best have reached a consensus that at x point we draw the line between human and non-human. These lines are artificial, imposed on the data by theorists, and not all agree with their exact placement. However, the whole construct holds together nicely, and the majority of paleontology and human biology is working out some of the finer details.
Now you may not agree with the conclusion, but you have to do a lot of work to catch up with where science is at any given time. It is not very productive to sit on the sidelines, unfamiliar with the logic, methods, data, and theories of any particular science, and dispute the conclusions on unrelated or inapplicable grounds.
Two more points: to be a useful hypothesis or theory, you need to be able to make predictions. These predictions have to be testable and falsifiable. This can lead to new data. However, a theory can also be extended far beyond the actual data. This is where scientists have problems with ID. Saying "the intelligent designer did it all" overreaches the data, and leaves no place to apply a test.
Hope this helps.