So Intel has been making Core i5 processors for about a decade now. Your MacBook probably uses an Intel Core i5-5250U processor, which is a 5th generation mobile(laptop) processor. The latest Core i5 being used in current laptops is 8th gen. Using a common processor benchmark called PassMark, let's look at how your processor stacks up against the older and newer i5 chips.
Common 1st gen i5 processor: i5-430M @ 2.27GHz: 2097 points
The 5th gen core i5 in your Macbook: Core i5-5250U @ 1.60GHz: 3583 points
Common 8th gen i5 processor: Core i5-8250U @ 1.60GHz: 7678 points
If any >2.0GHz i5 processor will work, the i5 in your MacBook is roughly 1.7x faster than the minimum requirement. Unless it breaks or you find it too slow, I'd save the money and upgrade in a couple of years. Don't listen to anyone claiming it will or already is deteriorating. The battery probably doesn't last as long as when it was new, but those MacBooks can easily last 8-10 years if well kept.