And how long did the other 26 amendments take? I just checked the 26th as a random example and the source I read said it took 4 months from proposal to ratification by the States. I'm sure there are other quick examples.
I know it's hard to do. It's designed to be as solid as a humanly-designed piece of legislation can be. This is a good thing, and it is as it should be.
But it's still just a law made by men, and it can be amended - and can even be amended quickly if the will is there. I'm not saying it is changed constantly, just that it can be. The process is difficult, but the process does exist, and is used. It has been amended 27 times, and most of those amendments will have taken far less than 202 years, you just picked the one that took the most insane amount of time as your sole example. It truly is just another law - a law with a lot of extra protections around it, but still just another law.