Ethereum took the basic ideas (and probably a lot of code) from bitcoin to add more features to it.

Many other coins also attempt to make slight changes or add features to try to give their coin a selling point, but a lot of the time those features are poorly thought out, not well coded or not much more than a gimmick.

But if you find a coin with good features that actually does what it's supposed to, it could be worth a lot someday (but there's no guarantee.)

Now, what you're talking about everyone having their own coins, most of those are actually "tokens." They usually won't have their own blockchain, but are created on another blockchain like ethereum. Most of these won't have any technological use - or much use at all for that matter - but their use will depend on what the creator of those tokens plan to do with them.

For example, a cryptocurrency exchange might create a token and use that to give users reduced fees. From a technological point the token doesn't really do anything, but it has a use because the exchange that issued the token makes it useful. So in exchange for providing some seed funding for the exchange and creating a reason for themselves to stick around and use the exchange, the exchange offers them a discount and possibly a growing investment.

So that's a simple one. But now let's say a celebrity makes a token. Does it do anything? It depends if the celebrity does anything with it. Maybe they'll use it as a currency or token that can be exchanged for special meetings or concerts or early access to some kind of art or whatever else. Or maybe they'll just issue it and be lazy and not do much with it. Who knows.

So finally, will there be a point to this if EVERYONE is trying to make their own token for every possible reason they can think of? Maybe, maybe not. Time will tell what happens.