yann,
Before you acquire at least a reasonably good idea of the Buddha’s Teaching, you are in no position to even have an opinion on whether “it is very safe to assume that they do not resemble 100% the original teachings”. Read the sections on the Site as Lal suggested. Then, THEN, ‘one should be able to think for himself and examine carefully what he believes’ By all means examine the Teaching, doubt It even, but be sure you have the main facts first. I too harboured this doubt at one time, so it is not condemning, as long as one is bent on resolving the issue.
The Teaching was written down by Arahants. They are the model, the very personification of Perfection, excluding, of course, a Buddha Himself. Once you see who or what an Arahant is, it will seem to you absurd,inconceivable, that Arahants could in any way twist the truth, or be agents of that, even unknowingly.
Once you get a good picture of the Teaching, examine it, reflect on it and based on that you SEE: ‘Here is what Reality is all about. At last! This is the Way. This is what I will pursue my whole life through’, you have gone for Refuge in the Buddha, the Dhamma and the Sangha. You are free of the apayas.
May you attain it soon. How soon is entirely up to you.