I agree with most comments here.

The cosmetics will change nearly every year in some small way. Also, minor technological changes will crop up every couple of years.

The last significant change in technology was integrated shifters. Everything since then has been incremental at best.

However, with that said, a component from a few years ago may, or may not work if mixed into a current component set. At least it may not work as well as a modern component... due for example to things like chain width changes from 9 to 10 speed etc.

I just had a bike built with 105 components. If I had been able to find a new old stock 9 speed 105 group, I wouldn't have hesitated to build with it since 9 cogs is plenty fpr me (in fact, 7 or 8 would be fine).

So, if I were to find older stuff in a parts bin that is in new shape, I wouldn't hesitate to use it.