Ok, so that is over less than 100 years (as an absolute upper bound).
Now imagine what changes might accumulate over 10 times that time, 1000 years.
What about, a hundred times that time, 10,000 years?
A thousand times? 100,000 years?
What about thirty seven million times that time? 3,700,000,000 years?
You must at least see the plausibility of common descent here, right? There are enough ways for changes to happen, there is natural selection, and there is enough time. Even if common descent is wrong, it's at least plausible. But, given all the evidence for it, we hit the realm of probable. In fact, the evidence is so compelling and there is so much of it, it's pretty much a given in the scientific community.
But it seems like you're saying x organism didn't change much in a very short time, therefore x organism can't change very much in a very long time, and that seems like a massive fault in logic. I just don't get it. That you're willing to tell the worlds experts you think you understand this better than them makes me really think it's you that doesn't get this. Did that ever occur to you? Did you ever think that maybe you really should just defer to the experts here? I imagine you would if it was your doctor, your solicitor, your plumber, etc. even if you did have a crack at reading what they're reading.